[clang][NFC] Update test case struct-union-BE.c for opaque-pointers

[tingwang]

Summary

Update patterns in this test case to align with opaque-pointers, otherwise it will not be able to catch errors.

This is spotted during https://reviews.llvm.org/D133338 investigation. During test after removed !DirectTy->isStructTy(), this test case still passed.

clang/test/CodeGen/struct-union-BE.c

 void fstr(int n, ...) {
   struct tiny x;
   va_list ap;
   va_start (ap,n);
   x = va_arg (ap, struct tiny);
   if (x.c !=  10)
     abort();
   va_end (ap);
-// MIPS-NOT: %{{[0-9]+}} = getelementptr inbounds i8, i8* %argp.cur, i32 3
-// MIPS64-NOT: %{{[0-9]+}} = getelementptr inbounds i8, i8* %argp.cur, i64 7
-// ARM-NOT: %{{[0-9]+}} = getelementptr inbounds i8, i8* %argp.cur, i32 3
+// MIPS-NOT: %{{[0-9]+}} = getelementptr inbounds i8, ptr %argp.cur, i32 3
+// MIPS64-NOT: %{{[0-9]+}} = getelementptr inbounds i8, ptr %argp.cur, i64 7
+// ARM-NOT: %{{[0-9]+}} = getelementptr inbounds i8, ptr %argp.cur, i32 3
 }
 
 void funi(int n, ...) {
   union data x;
   va_list ap;
   va_start (ap,n);
   x = va_arg (ap, union data);
   if (x.c !=  10)
     abort();
   va_end (ap);
-// MIPS-NOT: %{{[0-9]+}} = getelementptr inbounds i8, i8* %argp.cur, i32 3
-// MIPS64-NOT: %{{[0-9]+}} = getelementptr inbounds i8, i8* %argp.cur, i64 7
-// ARM-NOT: %{{[0-9]+}} = getelementptr inbounds i8, i8* %argp.cur, i32 3
+// MIPS-NOT: %{{[0-9]+}} = getelementptr inbounds i8, ptr %argp.cur, i32 3
+// MIPS64-NOT: %{{[0-9]+}} = getelementptr inbounds i8, ptr %argp.cur, i64 7
+// ARM-NOT: %{{[0-9]+}} = getelementptr inbounds i8, ptr %argp.cur, i32 3
 }
 
 void foo(void) {
   struct tiny x[3];
   union data y;
   x[0].c = 10;
   fstr(1, x[0]);
   funi(1, y);
 }