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

[Dan Liew via cfe-commits]

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@@ -0,0 +1,12 @@
+// This reports a warning to follow the default behavior of ClangAs.
+// RUN: %clang -fexperimental-bounds-safety -x assembler -c %s -o /dev/null 2>&1 | FileCheck -check-prefix WARN %s
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delcypher wrote:

@rapidsna Maybe there should be a version of this part of the test that doesn't pass `-x <lang>` and instead passes to a `.s` file to make sure the right thing happens when in that case?

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