configure.ac: Add stanza for *-*-gnu* threads configuration.

configure.ac: Add stanza for *-*-gnu* threads configuration.

boehm-gc/
	* configure.ac: Add stanza for *-*-gnu* threads configuration.
	* configure: Regenerate.
	* include/gc_config.h.in: Likewise.
	* dyn_load.c (_GNU_SOURCE): Define for __GNU__.
	* include/gc_config_macros.h (_REENTRANT, GC_PTHREADS): Define for
	GC_GNU_THREADS.
	* include/private/gcconfig.h (DATASTART): Don't define for I386 &&
	HURD.
	(SIG_SUSPEND, SIG_THR_RESTART, SEARCH_FOR_DATA_START): Define for
	I386 && HURD.
	(UNIX_LIKE, REGISTER_LIBRARIES_EARLY): Define for HURD.
	* os_dep.c (GC_init_linux_data_start): Handle for HURD.
	* pthread_support.c (GC_thr_init): Add case for GC_GNU_THREADS.
	* specific.c: Use for GC_GNU_THREADS.
	* threadlibs.c: Add case for GC_GNU_THREADS.

From-SVN: r193142