deprecated build instructions for gnutls26

[pdesolver]

following your build on windows 8 running virtualbox with the most recent x64 debian, following the tutorial in the ghc-android/Readme.md root@debian:~/ghc-android# ./build fails with Unable to find a source for package for gnults26. I think this is because I used apt-get -y install libgnutls28-dev in place of your surgested lbgnults-dev which fails with; Package 'libgnutls-dev' has no installation candidate