postgis is not really set up for cross-compilation. It wants to run
cross-compiled programs to check proj and protobuf versions, so we
need to patch that in configure script.
The current patch added to do this will be annoying to maintain. I
tried patching the configure.ac script instead but got weird errors
that seemed to have more to do with the autoconf version we have in
the docker image.
Fixes https://github.com/termux/termux-packages/issues/8142
