Darwin (before 8) has a very messed up assert.h and uses __eprintf
which is very wrong.  This patch fixes that by adding an assert.h
which does not use __eprintf at all.

OK? Bootstrapped and tested on powerpc-darwin7.6.0 and fixes the
last two libjava failures.

Thanks,
Andrew Pinski

ChangeLog:
	* config.gcc (*-*-darwin*): Add t-darwin-pre8 for pre
	darwin 8 targets.
	* config/t-darwin-pre8: New file. Add assert.h to the	EXTRA_HEADERS.
	* config/darwin-assert.h: New file. Assert.h for darwin.