[clang] [WebAssembly] Enable musttail only when tail-call is enabled (PR #163618)

[Derek Schuff via cfe-commits]

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@@ -546,6 +546,8 @@ NetBSD Support
 WebAssembly Support
 ^^^^^^^^^^^^^^^^^^^
 
+- Fix a bug so that __has_attribute(musttail) should not be true anymore when notail is not enabled.
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dschuff wrote:

"when notail is not enabled" should that be something like "when Wasm tail-call is not enabled"?

https://github.com/llvm/llvm-project/pull/163618