Add tests for uwtable annotations on modules

Author: Darksonn

tests/codegen-llvm/force-no-unwind-tables.rs

@@ -9,3 +9,5 @@
 fn foo() {
     panic!();
 }
+
+// CHECK-NOT: !"uwtable"

tests/codegen-llvm/force-unwind-tables.rs

@@ -4,3 +4,5 @@
 
 // CHECK: attributes #{{.*}} uwtable
 pub fn foo() {}
+
+// CHECK: !{{[0-9]+}} = !{i32 7, !"uwtable", i32 2}