PR fortran/29828

	* trans.h (gfor_fndecl_string_minmax): New prototype.
	* trans-decl.c (gfor_fndecl_string_minmax): New variable.
	(gfc_build_intrinsic_function_decls): Create gfor_fndecl_string_minmax.
	* check.c (gfc_check_min_max): Allow for character arguments.
	* trans-intrinsic.c (gfc_conv_intrinsic_minmax_char): New function.
	(gfc_conv_intrinsic_function): Add special case for MIN and MAX
	intrinsics with character arguments.
	* simplify.c (simplify_min_max): Add simplification for character
	arguments.

	* intrinsics/string_intrinsics.c (string_minmax): New function
	and prototype.
	* gfortran.map (GFORTRAN_1.0): Add _gfortran_string_minmax

	* gfortran.dg/minmax_char_1.f90: New test.
	* gfortran.dg/minmax_char_2.f90: New test.
	* gfortran.dg/min_max_optional_4.f90: New test.

From-SVN: r127252