PR libfortran/20006

	PR libfortran/20006
	* gfortran.h: Add is_main_program member to symbol_attribute.
	* trans-decl: Add a gfor_fndecl_set_std tree.
	(gfc_build_builtin_function_decls): Create it.
	(gfc_generate_function_code): Add this call at the beginning of
	the main program.
	* trans.c (gfc_generate_code): Move main_program and attr.
	* trans.h: Add declaration for gfor_fndecl_set_std.

	* Makefile.am: Add file runtime/compile_options.c.
	* Makefile.in: Regenerate.
	* libgfortran.h: Create structure compile_options_t. Define the
	compile_options variable and GFC_STD_ macros.
	* runtime/compile_options.c: New file.
	* runtime/error.c (notify_std): New function.
	* runtime/main.c (init): Call init_compile_options during
	initialization.
	* io/format.c: Use the new notify_std function for the $
	descriptor extension.

	* gfortran.dg/runtime_warning_1.f90: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@102990 138bc75d-0d04-0410-961f-82ee72b054a4