Fix build-tools patching when it uses variables

Like:

	buildToolsVersion FOO_VERSION

fdroidserver/build.py

@@ -442,7 +442,7 @@ def adapt_gradle(build_dir):
             if not os.path.isfile(path):
                 continue
             logging.debug("Adapting %s at %s" % (filename, path))
-            common.regsub_file(r"""(\s*)buildToolsVersion([\s=]+)['"].*""",
+            common.regsub_file(r"""(\s*)buildToolsVersion([\s=]+).*""",
                                r"""\1buildToolsVersion\2'%s'""" % config['build_tools'],
                                path)