Add __name__ == '__main__' block in freeze.py.

freeze.py now gets imported from freeze_tests.py, and shouldn't run its own
setup in that case.

scripts/freeze.py

@@ -94,7 +94,9 @@ executable = cx.Executable('qutebrowser/__main__.py', base=base,
                            icon=os.path.join(BASEDIR, 'icons',
                                              'qutebrowser.ico'))
 
-try:
+
+if __name__ == '__main__':
+    try:
         setupcommon.write_git_file()
         cx.setup(
             executables=[executable],
@@ -106,7 +108,7 @@ try:
             },
             **setupcommon.setupdata
         )
-finally:
+    finally:
         path = os.path.join(BASEDIR, 'qutebrowser', 'git-commit-id')
         if os.path.exists(path):
             os.remove(path)