Add the testcase from PR8

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9669 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstCombine/cast-set.ll

@@ -47,3 +47,9 @@ bool %test6(bool %A) {
 	%C = setne int %B, 0
 	ret bool %C
 }
+
+bool %test7(sbyte* %A) {
+	%B = cast sbyte* %A to int*
+	%C = seteq int* %B, null
+	ret bool %C
+}