[clang] [Clang][Sema]:Fix musttail attribute on a function with not_tail_called attribute has no warning/error (PR #134465)

[via cfe-commits]

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@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -verify -fsyntax-only %s
+
+int __attribute__((not_tail_called)) foo1(int a) {
+    return a + 1;  
+}
+
+
+int foo2(int a) {
+    [[clang::musttail]] 
+    return foo1(a);  // expected-error{{cannot perform a tail call to function'musttail' because its signature is incompatible with the calling function}}
----------------
MillePlateaux wrote:

> This diagnostic seems odd to me because of `function'musttail'` Is there really no whitespace there?

@AaronBallman Since we reuse ``err_musttail_mismatch``, and the function itself does not have spaces, I tried to add spaces , but the test case did not pass.I've pasted the code below.

```cpp
def err_musttail_mismatch : Error<
  "cannot perform a tail call to function%select{| %1}0 "
  "because its signature is incompatible with the calling function">;

https://github.com/llvm/llvm-project/pull/134465