[clang] [Clang][Interp] Implement constexpr vector unary operators +, -, ~, ! (PR #105996)

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+// RUN: %clang_cc1 %s -triple x86_64-linux-gnu -Wno-uninitialized -std=c++14 -fsyntax-only -verify
+// RUN: %clang_cc1 %s -triple x86_64-linux-gnu -fexperimental-new-constant-interpreter -Wno-uninitialized -std=c++14 -fsyntax-only -verify
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yronglin wrote:

It has no effect in the current test, just to keep it the same as test/SemaCXX/constexpr-vectors.cpp.

https://github.com/llvm/llvm-project/pull/105996