gcc.h (lang_specific_driver): Constify second argument.

gcc.h (lang_specific_driver): Constify second argument.

	* gcc.h (lang_specific_driver): Constify second argument.
	* gcc.c (translate_options, process_command, main): Likewise.
	Constify variables to match.  Cast second argument to
	pexecute.

	* cppspec.c, gccspec.c, g++spec.c, g77spec.c, jvspec.c: Adjust
	type of second argument to lang_specific_driver, and update
	code as necessary.

From-SVN: r35433