Revert to libgcc for sparc64.

I've had a report of a sparc64 system where cc1 generates illegal
instructions. We still have to diagnose this properly, but instead of
hosing all sparc64 boxes out there, fall back to libgcc to prevent more
damage.

Reported by:	Florian Smeets

gnu/lib/libgcc/Makefile

@@ -15,6 +15,10 @@ MK_SSP=	no
 
 .include "${.CURDIR}/../../usr.bin/cc/Makefile.tgt"
 
+.if ${TARGET_CPUARCH} == "sparc64"
+LIB=		gcc
+.endif
+
 .PATH: ${GCCDIR}/config/${GCC_CPU} ${GCCDIR}/config ${GCCDIR}
 
 CFLAGS+=	-DIN_GCC -DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED \

lib/libcompiler_rt/Makefile

@@ -147,11 +147,13 @@ SRCS+=	${file}.c
 . endif
 .endfor
 
-.if ${MK_INSTALLLIB} != "no"
+.if ${MACHINE_CPUARCH} != "sparc64"
+. if ${MK_INSTALLLIB} != "no"
 SYMLINKS+=libcompiler_rt.a ${LIBDIR}/libgcc.a
-.endif
-.if ${MK_PROFILE} != "no"
+. endif
+. if ${MK_PROFILE} != "no"
 SYMLINKS+=libcompiler_rt_p.a ${LIBDIR}/libgcc_p.a
+. endif
 .endif
 
 .include <bsd.lib.mk>