Add a failing test, see #7574.

Signed-off-by: Austin Seipp <aseipp@pobox.com>

testsuite/tests/codeGen/should_compile/T7574.cmm

+#include "Cmm.h"
+
+testLiteralBranch (W_ dst, W_ src)
+{
+  if (1) {
+    prim %memcpy(dst, src, 1024, 4);
+  } else {
+    prim %memcpy(dst, src, 512, 8);
+  }
+  return ();
+}

testsuite/tests/codeGen/should_compile/all.T

@@ -20,3 +20,4 @@ test('massive_array',
      [ when(arch('i386'), omit_ways(['llvm', 'optllvm'])) ],
      compile, ['-fPIC'])
 test('T7237', normal, compile, [''])
+test('T7574', [cmm_src, expect_broken(7574), omit_ways(['llvm', 'optllvm'])], compile, [''])