[SPARC32]: Add __cmpdi2() libcall implementation ala. MIPS.

Device mapper generates calls to this with recent versions
of gcc.

Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/lib/Makefile

@@ -8,6 +8,7 @@ lib-y := mul.o rem.o sdiv.o udiv.o umul.o urem.o ashrdi3.o memcpy.o memset.o \
          strlen.o checksum.o blockops.o memscan.o memcmp.o strncmp.o \
 	 strncpy_from_user.o divdi3.o udivdi3.o strlen_user.o \
 	 copy_user.o locks.o atomic.o \
-	 lshrdi3.o ashldi3.o rwsem.o muldi3.o bitext.o
+	 lshrdi3.o ashldi3.o rwsem.o muldi3.o bitext.o \
+	 cmpdi2.o
 
 obj-y += iomap.o atomic32.o