Prune MSYS2 packages pre-installed.

MSYS2 Git is not normally needed.  GfW is already installed.

I'm not sure why I installed zip, but unzip can be avoided since I'm
already (ab)using the bsdtar that comes with Windows to extract one zip
file, may as well use it for that one too.

A potential future reduction of pakages would be to switch from
-toolchain to -cc (or -clang).

See also msys2/msys2-autobuild#87

msys2-runner-setup/setupscripts/setup.cmd

@@ -36,13 +36,13 @@ C:\msys64\usr\bin\sed.exe -i -e 's/^^\(SigLevel\s\+=\s\+Required\)\s*$/\1 Databa
 CALL C:\msys64\msys2_shell.cmd -defterm -no-start -c "pacman --noconfirm --overwrite '*' -Syuu"
 REM the caret is messing with CMD parsing, try it another way
 C:\msys64\usr\bin\sed.exe -i -e '/^^# \[clangarm64\]/,/^^$/ s/^^# //g' /etc/pacman.conf
-CALL C:\msys64\msys2_shell.cmd -defterm -no-start -c "pacman --noconfirm --overwrite '*' -Sy --needed base-devel git mingw-w64-clang-aarch64-toolchain procps-ng psmisc zip unzip vim etc-update"
+CALL C:\msys64\msys2_shell.cmd -defterm -no-start -c "pacman --noconfirm --overwrite '*' -Sy --needed base-devel mingw-w64-clang-aarch64-toolchain procps-ng psmisc vim etc-update"
 CALL C:\msys64\msys2_shell.cmd -defterm -no-start -c "pacman --noconfirm -Scc"
 CALL C:\msys64\msys2_shell.cmd -defterm -no-start -c "echo export EDITOR=vim >> ~/.bash_profile"
 
 curl -Lo actions-runner-arm64.zip "https://github.com/actions/runner/releases/download/v%RUNNERVERSION%/actions-runner-win-arm64-%RUNNERVERSION%.zip"
 MKDIR C:\runner
-CALL C:\msys64\msys2_shell.cmd -defterm -no-start -here -c "unzip -o actions-runner-arm64.zip -d /c/runner"
+tar -C C:\runner -xvf actions-runner-arm64.zip
 CD /D C:\runner
 CALL config.cmd --unattended --url %RUNNERREGURL% --token %RUNNERREGTOKEN% --replace --disableupdate --ephemeral --labels "%RUNNERLABELS%"