utils.zsh: Enable debug symbols for ObjC

[PatTheMav]

Description

Adds necessary compiler arguments to emit debug symbols in release builds for ObjC and ObjC++.

Motivation and Context

To force CMake-based projects to emit debug symbols even in release configuration, the -g argument needs to be explicitly added to the global CMAKE_<LANGUAGE>_FLAGS_RELEASE variable.

This was done for C and C++ already, but not for ObjC and ObjC++ (which are correctly treated as separate languages by CMake). This is required to make Qt plugins like the cocoa platform plugin "debuggable" with dSYM files loaded into a debugger.

How Has This Been Tested?

Built Qt locally and confirmed that functions called within the Cocoa platform plugin were correctly debuggable with source code available on the local machine.

Types of changes

• Tweak (non-breaking change to improve existing functionality)

Checklist:

• I have read the contributing document.
• My code has been run through clang-format.
• My code follows the project's style guidelines
• My code is not on the master branch.
• My code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.