[libc] [llvm] [libc][math][c23] Add rsqrtf() function (PR #159615)

[via llvm-commits]

================
@@ -2296,6 +2296,19 @@ libc_support_library(
     ],
 )
 
+libc_support_library(
+    name = "__support_math_rsqrtf",
+    hdrs = ["src/__support/math/rsqrtf.h"],
+    deps = [
+        ":__support_fputil_cast",
+        ":__support_fputil_fenv_impl",
+        ":__support_fputil_fp_bits",
----------------
overmighty wrote:

```suggestion
        ":__support_fputil_fp_bits",
        ":__support_fputil_sqrt",
```

https://github.com/llvm/llvm-project/pull/159615