Most people seem to use the traditional way of calling gpg directly
from mutt, and the gpgme integration doesn't seem to work at least
in Termux, so remove it. Closes#152.
Also update the version of the neomutt patches used.
- Fix hardlink usage which doesn't work on Android 6.
- Enable header cache and depend on gdbm.
- Specify $PREFIX/bin/sh as exec shell to avoid trying /bin/sh.
Fixes#84.
- Avoid building bundled&broken (v)snprintf functions.
