* treewide: http -> https sources
This updates the source urls of all top-level packages from http to
https where possible.
* buildtorrent: fix url and tab -> spaces
When copying generic-nix to generic-cmake.nix, an explicit
configurePhase was added, but it doesn't use the existing
configureFlags.
Fixing this allowed removing the postBuild fixup of the path to
libgdiplus.so, since the --with-libgdiplus option already handles that.
