[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/cmpdi2.c

@@ -0,0 +1,27 @@
+#include <linux/module.h>
+
+#include "libgcc.h"
+
+word_type __cmpdi2(long long a, long long b)
+{
+	const DWunion au = {
+		.ll = a
+	};
+	const DWunion bu = {
+		.ll = b
+	};
+
+	if (au.s.high < bu.s.high)
+		return 0;
+	else if (au.s.high > bu.s.high)
+		return 2;
+
+	if ((unsigned int) au.s.low < (unsigned int) bu.s.low)
+		return 0;
+	else if ((unsigned int) au.s.low > (unsigned int) bu.s.low)
+		return 2;
+
+	return 1;
+}
+
+EXPORT_SYMBOL(__cmpdi2);