[ATfE] Enable locale in libc++ with LLVM-libc

This is required for std::cout. This patch relies on the following:
llvm/llvm-project#156330
llvm/llvm-project#156331

Author: saturn691

arm-software/embedded/arm-runtimes/CMakeLists.txt

@@ -858,7 +858,6 @@ if(ENABLE_CXX_LIBS)
             -DLIBCXX_ENABLE_THREADS=OFF
             -DLIBCXX_ENABLE_WIDE_CHARACTERS=OFF
             -DLIBCXX_ENABLE_FILESYSTEM=OFF
-            -DLIBCXX_ENABLE_LOCALIZATION=OFF
             -DLIBCXX_ENABLE_UNICODE=OFF
             -DLIBUNWIND_ENABLE_THREADS=OFF
             -DLIBCXXABI_ENABLE_EXCEPTIONS=${ENABLE_EXCEPTIONS}

arm-software/embedded/llvmlibc-samples/src/cpp-baremetal-semihosting-llvmlibc/hello.cpp

@@ -4,7 +4,8 @@
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <cstdio> // iostream is not supported yet
+#include <cstdio>
+#include <iostream>
 #include <vector>
 
 int test_exceptions(int i)
@@ -30,7 +31,7 @@ int main(void) {
   try {
     int result = test_exceptions(0);
   } catch (...) {
-    std::puts("Exception caught.");
+    std::cout << "Exception caught." << std::endl;
   }
   return 0;
 }