MacOS ARM builds are missing m17_decoder

[jancona]

Hardware

• CPU: Apple M3
• RAM: 24 GB
• GPU:
• SDR: RTL-SDR

Software

• Operating System: MacOS Sequoia 15.2
• SDR++: SDR++ v1.2.1 20:22:47, Jan 5 2025

Bug Description
The M17 Decoder is not packaged with the release. See Discord discussion.

Steps To Reproduce

1. Run SDR++
2. Attempt to select m17_decoder in the Module Manager drop-down list, but it's not there.

Additional info
The m17_decoder was removed from the MacOS ARM build because of build failures like this:

In file included from /Users/runner/work/SDRPlusPlus/SDRPlusPlus/decoder_modules/m17_decoder/src/m17dsp.h:8:
/opt/homebrew/Cellar/codec2/1.2.0/include/codec2/codec2.h:31:10: fatal error: 'codec2/version.h' file not found
#include <codec2/version.h>
         ^~~~~~~~~~~~~~~~~~
1 warning and 1 error generated.

Because the MacOS Intel build is unaffected, this may be related to the ARM version of Homebrew being installed in /opt/homebrew instead of /usr/local on Intel Macs. I was able to get a clean build by defining CPATH in the build environment. See jancona@e85f3fb. There's probably a cleaner solution involving CMake and/or Homebrew, but finding it is beyond my skills.