* gfortran.h (gfc_options_t): Add flag_allow_leading_underscore.
	* lang.opt: Add -fallow-leading-underscore.
	* match.c (gfc_match_name): Allow leading underscore in symbol
	name if -fallow-leading-underscore is used.
	* symbol.c (gfc_get_default_type): Add special case for symbol
	names beginning with an underscore.
	* trans-decl.c (gfc_get_extern_function_decl,
	gfc_build_intrinsic_function_decls): Add _gfortran prefix to
	library symbols selected_int_kind, selected_real_kind and 
	all specifics.
	* options.c (gfc_init_options, gfc_handle_option): Handle the
	new -fallow-leading-underscore option.

	* m4/misc_specifics.m4: Add _gfortran prefix to specific names.
	* m4/specific2.m4: Likewise.
	* m4/specific.m4: Likewise.
	* intrinsics/f2c_specifics.F90: Likewise.
	* intrinsics/selected_int_kind.f90: Add _gfortran prefix.
	* intrinsics/selected_real_kind.f90: Likewise.
	* intrinsics/dprod_r8.f90: Likewise.
	* Makefile.am: Add -fallow-leading-underscore to the
	gfor_specific_src files, as well as selected_real_kind.F90
	and selected_int_kind.F90
	* Makefile.in: Regenerate.
	* generated/_sqrt_c8.F90: Regenerate.
	* generated/_sign_r16.F90: Regenerate.
	* generated/_log_c16.F90: Regenerate.
	* generated/_sin_c10.F90: Regenerate.
	* generated/_tanh_r4.F90: Regenerate.
	* generated/_tanh_r8.F90: Regenerate.
	* generated/_log10_r10.F90: Regenerate.
	* generated/_aimag_c4.F90: Regenerate.
	* generated/_sign_r4.F90: Regenerate.
	* generated/_aimag_c8.F90: Regenerate.
	* generated/_sign_r8.F90: Regenerate.
	* generated/_mod_i4.F90: Regenerate.
	* generated/_cos_r16.F90: Regenerate.
	* generated/_aint_r10.F90: Regenerate.
	* generated/_mod_i8.F90: Regenerate.
	* generated/_abs_i16.F90: Regenerate.
	* generated/_sqrt_c10.F90: Regenerate.
	* generated/_atan2_r4.F90: Regenerate.
	* generated/_cos_c4.F90: Regenerate.
	* generated/_atan_r16.F90: Regenerate.
	* generated/_tanh_r10.F90: Regenerate.
	* generated/_atan2_r8.F90: Regenerate.
	* generated/_cos_c8.F90: Regenerate.
	* generated/_exp_r4.F90: Regenerate.
	* generated/_log_r10.F90: Regenerate.
	* generated/_exp_r8.F90: Regenerate.
	* generated/_abs_r4.F90: Regenerate.
	* generated/_abs_r8.F90: Regenerate.
	* generated/_sin_r16.F90: Regenerate.
	* generated/_tan_r4.F90: Regenerate.
	* generated/_tan_r8.F90: Regenerate.
	* generated/_sign_i4.F90: Regenerate.
	* generated/_sign_i8.F90: Regenerate.
	* generated/_exp_c16.F90: Regenerate.
	* generated/_sqrt_r16.F90: Regenerate.
	* generated/_conjg_c4.F90: Regenerate.
	* generated/_conjg_c8.F90: Regenerate.
	* generated/_dim_r16.F90: Regenerate.
	* generated/_mod_r10.F90: Regenerate.
	* generated/_abs_c10.F90: Regenerate.
	* generated/_conjg_c16.F90: Regenerate.
	* generated/_tan_r16.F90: Regenerate.
	* generated/_asinh_r10.F90: Regenerate.
	* generated/_abs_i4.F90: Regenerate.
	* generated/_abs_i8.F90: Regenerate.
	* generated/_acos_r10.F90: Regenerate.
	* generated/_exp_r10.F90: Regenerate.
	* generated/_acosh_r16.F90: Regenerate.
	* generated/_atan2_r16.F90: Regenerate.
	* generated/_cos_c16.F90: Regenerate.
	* generated/_mod_i16.F90: Regenerate.
	* generated/_asin_r4.F90: Regenerate.
	* generated/_anint_r16.F90: Regenerate.
	* generated/_asin_r8.F90: Regenerate.
	* generated/_aimag_c10.F90: Regenerate.
	* generated/_exp_c4.F90: Regenerate.
	* generated/_sinh_r10.F90: Regenerate.
	* generated/_exp_c8.F90: Regenerate.
	* generated/_log10_r4.F90: Regenerate.
	* generated/_log10_r8.F90: Regenerate.
	* generated/_abs_c4.F90: Regenerate.
	* generated/_abs_r16.F90: Regenerate.
	* generated/_abs_c8.F90: Regenerate.
	* generated/_asin_r10.F90: Regenerate.
	* generated/_sign_r10.F90: Regenerate.
	* generated/_atanh_r16.F90: Regenerate.
	* generated/_log_c10.F90: Regenerate.
	* generated/_cosh_r16.F90: Regenerate.
	* generated/_sin_c16.F90: Regenerate.
	* generated/_cos_r10.F90: Regenerate.
	* generated/_log10_r16.F90: Regenerate.
	* generated/_aint_r16.F90: Regenerate.
	* generated/_acos_r4.F90: Regenerate.
	* generated/_acos_r8.F90: Regenerate.
	* generated/_sqrt_c16.F90: Regenerate.
	* generated/_acosh_r4.F90: Regenerate.
	* generated/_atan_r10.F90: Regenerate.
	* generated/_acosh_r8.F90: Regenerate.
	* generated/_sign_i16.F90: Regenerate.
	* generated/_tanh_r16.F90: Regenerate.
	* generated/_log_r4.F90: Regenerate.
	* generated/_log_r8.F90: Regenerate.
	* generated/_sin_r4.F90: Regenerate.
	* generated/_sin_r8.F90: Regenerate.
	* generated/_log_r16.F90: Regenerate.
	* generated/_sin_r10.F90: Regenerate.
	* generated/_sqrt_r4.F90: Regenerate.
	* generated/_exp_c10.F90: Regenerate.
	* generated/_sqrt_r8.F90: Regenerate.
	* generated/_asinh_r4.F90: Regenerate.
	* generated/_sqrt_r10.F90: Regenerate.
	* generated/_asinh_r8.F90: Regenerate.
	* generated/_dim_r4.F90: Regenerate.
	* generated/_dim_r8.F90: Regenerate.
	* generated/_dim_r10.F90: Regenerate.
	* generated/_cosh_r4.F90: Regenerate.
	* generated/_conjg_c10.F90: Regenerate.
	* generated/_tan_r10.F90: Regenerate.
	* generated/_cosh_r8.F90: Regenerate.
	* generated/_mod_r16.F90: Regenerate.
	* generated/_abs_c16.F90: Regenerate.
	* generated/_cos_r4.F90: Regenerate.
	* generated/_asinh_r16.F90: Regenerate.
	* generated/_cos_r8.F90: Regenerate.
	* generated/_atanh_r4.F90: Regenerate.
	* generated/_atanh_r8.F90: Regenerate.
	* generated/_acos_r16.F90: Regenerate.
	* generated/_anint_r4.F90: Regenerate.
	* generated/_acosh_r10.F90: Regenerate.
	* generated/_anint_r8.F90: Regenerate.
	* generated/_exp_r16.F90: Regenerate.
	* generated/_mod_r4.F90: Regenerate.
	* generated/_cos_c10.F90: Regenerate.
	* generated/_atan2_r10.F90: Regenerate.
	* generated/_dim_i16.F90: Regenerate.
	* generated/_mod_r8.F90: Regenerate.
	* generated/_anint_r10.F90: Regenerate.
	* generated/_aint_r4.F90: Regenerate.
	* generated/_aint_r8.F90: Regenerate.
	* generated/_dim_i4.F90: Regenerate.
	* generated/_sinh_r4.F90: Regenerate.
	* generated/_log_c4.F90: Regenerate.
	* generated/_dim_i8.F90: Regenerate.
	* generated/_sinh_r8.F90: Regenerate.
	* generated/_log_c8.F90: Regenerate.
	* generated/_sin_c4.F90: Regenerate.
	* generated/_sin_c8.F90: Regenerate.
	* generated/misc_specifics.F90: Regenerate.
	* generated/_abs_r10.F90: Regenerate.
	* generated/_aimag_c16.F90: Regenerate.
	* generated/_atan_r4.F90: Regenerate.
	* generated/_sinh_r16.F90: Regenerate.
	* generated/_atan_r8.F90: Regenerate.
	* generated/_atanh_r10.F90: Regenerate.
	* generated/_cosh_r10.F90: Regenerate.
	* generated/_sqrt_c4.F90: Regenerate.
	* generated/_asin_r16.F90: Regenerate.

From-SVN: r121007