[preprocessor/91639] #includes at EOF

[preprocessor/91639] #includes at EOF

https://gcc.gnu.org/ml/gcc-patches/2019-09/msg00280.html
	libcpp/
	PR preprocessor/91639
	* directives.c (do_include_common): Tell lexer we're a #include.
	* files.c (_cpp_stack_file): Lexer will have always incremented.
	* internal.h (struct cpp_context): Extend in_directive's
	semantics.
	* lex.c (_cpp_lex_direct): Increment line for final \n when lexing
	for an ISO #include.
	* line-map.c (linemap_line_start): Remember if we overflowed.

	gcc/testsuite/
	PR preprocessor/91639
	* c-c++-common/cpp/pr91639.c: New.
	* c-c++-common/cpp/pr91639-one.h: New.
	* c-c++-common/cpp/pr91639-two.h: New.

From-SVN: r275402