gnulib-tool.py: Follow gnulib-tool changes, part 48.
Follow gnulib-tool change
2019-01-23 Bruno Haible <bruno@clisp.org>
gnulib-tool: Support running testdirs on Android.
* pygnulib/GLError.py (GLError.__init__, GLError.__repr__): Add errno 20
to print an error if patching build-aux/test-driver fails.
* pygnulib/main.py (main): Likewise.
* pygnulib/GLTestDir.py (_patch_test_driver): New private function which
runs patch on build-aux/test-driver with build-aux/test-driver.diff.
(GLTestDir.execute, GLMegaTestDir.execute): Check for
build-aux/test-driver in each testdir and patch it after running
automake.