Build failure on macOS when using --disable-cocoa

Host environment

Operating system: macOS
OS/kernel version: 12.7.2 (but irrelevant)
Architecture: x86_64 (but irrelevant)
QEMU flavor: ?
QEMU version: 8.2.1
QEMU command line:
```
./configure --disable-cocoa
```

Description of problem

Build fails:

../qemu-8.2.1/meson.build:3741:13: ERROR: No host machine compiler for 'audio/coreaudio.m'

Steps to reproduce

On macOS run ./configure --disable-cocoa

Result:

Compiler for language objc skipped: feature cocoa disabled

../meson.build:3741:13: ERROR: No host machine compiler for 'audio/coreaudio.m'

Additional information

It seems your build script contains the assumption that an Objective-C compiler is not needed when the Cocoa UI is disabled, but it still appears to be needed to compile the CoreAudio code regardless of UI.

This was originally reported to MacPorts here: https://trac.macports.org/ticket/67984

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