[libc] [llvm] [libc][math][c23] Add {,u}fromfp{,x}{,f,l,f128} functions (PR #86003)

[via llvm-commits]

================
@@ -76,6 +76,7 @@ libc_support_library(
     deps = [
         ":LibcUnitTest",
         ":string_utils",
+        "//libc:__support_cpp_array",
----------------
lntue wrote:

Can you run bazel build and test to see if it works properly:
```
$ cd  ${llvm-project folder}/utils/bazel
$ bazel build --config=generic_clang --features=layering_check @llvm-project//libc/...
$ bazel test --config=generic_clang @llvm-project//libc/...
```

https://github.com/llvm/llvm-project/pull/86003