[BUG] Regression when building with C++ toolchain enabled - broken locale

[leducp]

Description / Steps to reproduce the issue

Since PR #13755, compilation is broken with arm-gcc at least (but probably all version) because public locale were moved to a .c file (which have no sense since it is a public API used by the GCC libstdc++ and llvm libxx).

On which OS does this issue occur?

[OS: Linux]

What is the version of your OS?

Debian testing

NuttX Version

master

Issue Architecture

[Arch: all]

Issue Area

[Area: OS Components]

Verification

• I have verified before submitting the report.

[leducp]

To test the regression, just add "#include " to any C++ file in a user app (like C++ hello world example") and build with GCC

Tester with:

• gcc version 13.3.1 20240614 (15:13.3.rel1-1) from Debian repo
• gcc version 12.3.1 20230626 (Arm GNU Toolchain 12.3.Rel1 (Build arm-12.35)) from ARM web site