* config.gcc (the unlabeled system switch statement): Add

	* config.gcc (the unlabeled system switch statement): Add
	generic configuration section to handle *-*-freebsd*.  Also,
	to match the system compiler, default to threading support (it
	may be disabled with the standard --disable-threads
	configuration-time switch).
	(i[34567]86-*-freebsd* in machine-specific section): Use it.
	(alpha*-*-freebsd* in machine-specific section): Likewise.

	* config/freebsd3.h: New file to expose FBSD_MAJOR macro (3).
	* config/freebsd4.h: New file to expose FBSD_MAJOR macro (4).
	* config/freebsd5.h: New file to expose FBSD_MAJOR macro (5).
	* config/freebsd6.h: New file to expose FBSD_MAJOR macro (6).
	* config/freebsd-nthr.h: New file to expose FBSD_NO_THREADS macro.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@42463 138bc75d-0d04-0410-961f-82ee72b054a4