* cygtls.h (_tlsbase): Temporary workaround for GCC bug.
	(_tlsbase): Ditto.
	* cygwin64.din: Set BASE temporariliy to address < 32 bit to workaround
	GDB bug.
	* dcrt0.cc (child_info_fork::alloc_stack): Temporary workaround for GCC
	bug.
	(dll_crt0_1): Ditto.
	* miscfuncs.cc (memset): Temporary workaround missing MSABI function in
	newlib.
	(memcpy): Ditto.
	* include/cygwin/config.h (__getreent): Drop definition for x86_64 to
	workaround GCC bug.