parser: no option to specify configfile - breaks testcases

[Christian Boltz]

apparmor_parser doesn't have a way to specify which configfile to read - it's hardcoded to read /etc/apparmor/parser.conf.

This breaks testcases like "test with default config - shouldn't create a cache file" if the config file in /etc/ contains "write-cache", and might also break other testcases that depend on the default config.

We need something like
    apparmor_parser --configfile ./tests/parser.conf