Don't warn on dollars in builtin macro definitions,

Don't warn on dollars in builtin macro definitions,

	e.g. __REGISTER_PREFIX__.
	* cpphash.h (struct cpp_reader): Move member warn_dollars...
	* cpplib.h (struct cpp_options): ...to here.  Change type to
	unsigned char.
	* cppinit.c (cpp_create_reader): Set it to 1 here.
	(post_options): Don't set it here.
	* c-opts.c (c_common_init_options): Reset it to 0 here.
	(finish_options): Set it here.
	* cpplex.c (forms_identifier_p): Tweak for new location of
	warn_dollars.

From-SVN: r67824