Don't use PKG compression

xz can be fairly costly and isn't usefull intermediate packages
files.

aur.py

@@ -144,7 +144,7 @@ def install_with_makepkg(module, package):
         os.chdir(format(result['Name']))
         if module.params['skip_pgp_check']:
             use_cmd['makepkg'].append('--skippgpcheck')
-        rc, out, err = module.run_command(use_cmd['makepkg'], check_rc=True)
+        rc, out, err = module.run_command(use_cmd['makepkg'], environ_update={'PKGEXT': 'pkg.tar'}, check_rc=True)
         os.chdir(current_path)
     return (rc, out, err)