[llvm] [libc] Refactor scanf reader to match printf (PR #66023)

[via llvm-commits]

================
@@ -126,6 +126,10 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.stdio.snprintf
     libc.src.stdio.vsprintf
     libc.src.stdio.vsnprintf
+    #TODO: Check if scanf can be enabled on aarch64
----------------
michaelrj-google wrote:

tested, it passes.

https://github.com/llvm/llvm-project/pull/66023