Update the test

Author: AaronBallman

clang/test/ASTMerge/enum/test2.c

@@ -1,9 +1,7 @@
 // RUN: %clang_cc1 -std=c23 -emit-pch -o %t.1.ast %S/Inputs/enum3.c
 // RUN: %clang_cc1 -std=c23 -emit-pch -o %t.2.ast %S/Inputs/enum4.c
-// RUN: not %clang_cc1 -std=c23 -ast-merge %t.1.ast -ast-merge %t.2.ast -fsyntax-only %s 2>&1 | FileCheck %s
+// RUN: %clang_cc1 -std=c23 -ast-merge %t.1.ast -ast-merge %t.2.ast -fsyntax-only %s 2>&1 | FileCheck %s
 
-// FIXME: this error should not happen!
-// CHECK: error: type 'struct __NSConstantString_tag' has an attribute which currently causes the types to be treated as though they are incompatible
 // CHECK: enum3.c:2:6: warning: type 'enum E1' has incompatible definitions in different translation units
 // CHECK: enum4.c:2:6: note: enumeration 'E1' missing fixed underlying type here
 // CHECK: enum3.c:2:6: note: enumeration 'E1' has fixed underlying type here
@@ -12,5 +10,5 @@
 // CHECK: enum3.c:6:6: note: enumeration 'E2' missing fixed underlying type here
 // CHECK: enum3.c:11:6: warning: type 'enum E3' has incompatible definitions in different translation units
 // CHECK: enum3.c:11:6: note: enumeration 'E3' declared with incompatible fixed underlying types ('long' vs. 'short')
-// CHECK: 3 warnings and 1 error generated
+// CHECK: 3 warnings generated