re PR preprocessor/29612 (gcc --save-temps does not give "multi-character character constant" error)

	PR preprocessor/29612
	* directives.c (do_linemarker): Set pfile->buffer->sysp always, not
	only when new_sysp is non-zero.

	* gcc.dg/cpp/pr29612-1.c: New test.
	* gcc.dg/cpp/pr29612-2.c: New test.

From-SVN: r120257