new testcase distilled from 177.mesa

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8766 91177308-0d34-0410-b5e6-96231b3b80d8

test/CFrontend/2003-09-30-StructLayout.c

@@ -0,0 +1,16 @@
+enum En {
+  ENUM_VAL
+};
+
+struct St {
+  unsigned char A;
+  enum En B;
+  unsigned char C;
+  enum En D;
+  float E;
+};
+
+
+void func(struct St* A) {
+  A->D = ENUM_VAL;
+}