target.def (addr_space): Add new diagnose_usage to hook vector.

target.def (addr_space): Add new diagnose_usage to hook vector.

gcc/
	* target.def (addr_space): Add new diagnose_usage to hook vector.
	* targhooks.c (default_addr_space_diagnose_usage): Add default
	implementation and...
	* targhooks.h (default_addr_space_diagnose_usage): ... its prototype.
	* c/c-parser.c (c_lex_one_token) [CPP_NAME]: If the token
	is some address space, call targetm.addr_space.diagnose_usage.
	* doc/tm.texi.in (Named Address Spaces): Add anchor for
	TARGET_ADDR_SPACE_DIAGNOSE_USAGE documentation.
	* doc/tm.texi: Regenerate.

From-SVN: r238514