[llvm] [libc][bazel] Add bazel targets for libc/include/... tests. (PR #141150)

[Alexey Samsonov via llvm-commits]

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@@ -71,6 +71,7 @@ libc_test_library(
         "//libc:llvm_libc_macros_stdfix_macros",
         "//llvm:Support",
     ],
+    alwayslink = True,
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vonosmas wrote:

What would happen if you try to link in this library to a test which already has `main()` before this change?

https://github.com/llvm/llvm-project/pull/141150