re PR fortran/18452 (Fortran options induces warning for fortran that needs preprocessing)

	PR fortran/18452

	* gcc/fortran/lang-specs.h: Pass -lang-fortran to the preprocessor.

	* gcc/c.opt: Add a -lang-fortran option.
	* gcc/c-opts.c: Add a lang_fortran flag.
	(c_common_init_options): Handling the -lang-fortran option.
	(c_common_handle_option): Add a case for Fortran options in
	preprocessing. Remove cases for -ffixed-form and
	-ffixed-line-length. Add a case for -lang-fortran.

From-SVN: r106483