Get rid of __LT_SPINLOCK_INIT

We got rid of LinuxThreads in 2005, but we didn't remove
__LT_SPINLOCK_INIT back then.  Do it now.

	* nptl/sysdeps/pthread/bits/libc-lockP.h [defined NOT_IN_libc
	&& !defined IS_IN_libpthread && __LT_SPINNOCK_INIT != 0]:
	Remove.