Fortran: Fix -Wno-missing-include-dirs handling [PR55534]

Fortran: Fix -Wno-missing-include-dirs handling [PR55534]

gcc/fortran/ChangeLog:

	PR fortran/55534
	* cpp.c: Define GCC_C_COMMON_C for #include "options.h" to make
	cpp_reason_option_codes available.
	(gfc_cpp_register_include_paths): Make static, set pfile's
	warn_missing_include_dirs and move before caller.
	(gfc_cpp_init_cb): New, cb code moved from ...
	(gfc_cpp_init_0): ... here.
	(gfc_cpp_post_options): Call gfc_cpp_init_cb.
	(cb_cpp_diagnostic_cpp_option): New. As implemented in c-family
	to match CppReason flags to -W... names.
	(cb_cpp_diagnostic): Use it to replace single special case.
	* cpp.h (gfc_cpp_register_include_paths): Remove as now static.
	* gfortran.h (gfc_check_include_dirs): New prototype.
	(gfc_add_include_path): Add new bool arg.
	* options.c (gfc_init_options): Don't set -Wmissing-include-dirs.
	(gfc_post_options): Set it here after commandline processing. Call
	gfc_add_include_path with defer_warn=false.
	(gfc_handle_option): Call it with defer_warn=true.
	* scanner.c (gfc_do_check_include_dir, gfc_do_check_include_dirs,
	gfc_check_include_dirs): New. Diagnostic moved from ...
	(add_path_to_list): ... here, which came before cmdline processing.
	Take additional bool defer_warn argument.
	(gfc_add_include_path): Take additional defer_warn arg.
	* scanner.h (struct gfc_directorylist): Reorder for alignment issues,
	add new 'bool warn'.

libgfortran/ChangeLog:
	PR fortran/55534
	* configure.ac (AM_FCFLAGS): Add -Wno-missing-include-dirs.
	* configure: Regenerate.

libgomp/ChangeLog:
	PR fortran/55534
	* testsuite/libgomp.fortran/fortran.exp: Add -Wno-missing-include-dirs
	to ALWAYS_CFLAGS.
	* testsuite/libgomp.oacc-fortran/fortran.exp: Likewise.

gcc/testsuite/ChangeLog:
	* gfortran.dg/include_6.f90: Change dg-error to
	dg-warning and update pattern.
	* gfortran.dg/include_14.f90: New test.
	* gfortran.dg/include_15.f90: New test.
	* gfortran.dg/include_16.f90: New test.
	* gfortran.dg/include_17.f90: New test.
	* gfortran.dg/include_18.f90: New test.
	* gfortran.dg/include_19.f90: New test.
	* gfortran.dg/include_20.f90: New test.
	* gfortran.dg/include_21.f90: New test.