* c-tree.h: Remove declaration of poplevel.

	* tree.h: Remove declaration of approx_sqrt.

	* c-lex.c: Remove redundant declaration of asm_out_file.

	* flags.h: Remove declaration of warn_unknown_pragma and
	main_input_filename.

	* rtl.h: Remove functions from fold-const.c since they're already
	declared in tree.h.

	* regs.h: Remove redundant declaration of reg_names.

cp:

	* cp-tree.h: Remove duplicated declarations.

From-SVN: r68193