GitHub Actions (macOS): persist ccache's cache between runs

[ulmus-scott]

ccache does not appear to work on the macOS actions. I will attempt to enable and verify it on the macOS workflows.

[ulmus-scott]

on macOS:
(default) cache_dir = /Users/runner/Library/Caches/ccache

mythtv/.github/workflows/buildmaster.yml

Lines 31 to 36 in 9175b16

	- name: Check ccache
	uses: actions/cache@v2
	with:
	path: ~/.ccache
	key: ${{ matrix.os }}-${{ matrix.cc }}-ccache-${{ github.sha }}
	restore-keys: ${{ matrix.os }}-${{ matrix.cc }}-ccache

Line 34 is wrong for macOS.

Waiting for the second Action to complete.

[ctreleaven]

If a macOS user has installed ccache via MacPorts, your assumption will be invalid--the cache_dir will be ~/.ccache. I'm not sure where Homebrew or Fink place the cache. I think the correct thing to do is to ask ccache:

ccache --get-config cache_dir

Craig

[ulmus-scott]

@ctreleaven This only effects the GitHub Actions builds, not anyone working on a checked out copy on their local machine.

The GitHub builders use Homebrew:

mythtv/.github/workflows/buildmaster.yml

Line 52 in 630afc1

brew install pkg-config ccache qt5 nasm libsamplerate taglib lzo libcec libbluray fftw libass libhdhomerun dav1d x264 x265 libvpx openssl sound-touch

This was the easiest way I saw to enable ccache on the macOS GitHub Actions builders.

[ulmus-scott]

I decided to force the use of CCACHE_DIR=$HOME/.ccache instead of relying on fragile packaging defaults.