backport: re PR preprocessor/92296 (internal compiler error: Segmentation fault ...

backport: re PR preprocessor/92296 (internal compiler error: Segmentation fault  #pragma push_macro("__LINE__"))

	Backported from mainline
	2019-10-31  Jakub Jelinek  <jakub@redhat.com>

	PR preprocessor/92296
	* internal.h (struct def_pragma_macro): Add is_builtin bitfield.
	(_cpp_restore_special_builtin): Declare.
	* init.c (_cpp_restore_special_builtin): New function.
	* directives.c (do_pragma_push_macro): For NT_BUILTIN_MACRO
	set is_builtin and don't try to grab definition.
	(cpp_pop_definition): Use _cpp_restore_special_builtin to restore
	builtin macros.

	* c-c++-common/cpp/pr92296-1.c: New test.
	* c-c++-common/cpp/pr92296-2.c: New test.

From-SVN: r277987