abuild: Don't die when not in a git repository
If the APKBUILD file does not exist in a (reachable) repository, we currently fail. As we want to allow abuild to work in all circumstances, even without git (as can be seen in the git detection mechanism), also allow apk files to be generated outside of repositories.
Signed-off-by: Olliver Schinagl oliver@schinagl.nl