[clang] [Driver][BoundsSafety] Add -fbounds-safety-experimental flag (PR #70480)

[Fangrui Song via cfe-commits]

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@@ -0,0 +1,11 @@
+// RUN: %clang -c %s -### 2>&1 | FileCheck -check-prefix T0 %s
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MaskRay wrote:

`clang/test/Driver/clang_f_opts.c` mixes a lot of options. Newer `-fxxx` tests can go to a dedicated `clang/test/Driver/fxxx.c`

https://github.com/llvm/llvm-project/pull/70480