* cppfiles.c (open_include_file): If open(2) returns EMFILE or

	* cppfiles.c (open_include_file): If open(2) returns EMFILE or
	ENFILE, close all cached file descriptors and try again.
	(_cpp_execute_include): Keep a count of the number of times
	each header is included.
	(close_cached_fd): New function.
	* cpphash.h (struct include_file): Rename before to
	include_count; all users updated.  Make include_count and sysp
	unsigned short.
	* cppinit.c (cpp_finish): If -H, report headers that could use
	reinclude guards.
	(report_missing_guard): New function.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@34760 138bc75d-0d04-0410-961f-82ee72b054a4