ForgeFlower is better than Spigots FernFlower at decompiling the source.
However, in order to maintain the CraftBukkit patches, we must keep
using spigots for the primary.
However, for any file that we import on top of Spigots imported files
there is nothing stopping us from using better decompiled files.
So these changes will use ForgeFlower to maintain a better set of
decomped files, so anything we add on top of Paper can start off
in a better spot.
Rather than checking the platform or operating system, simply check if
the command exists. If the check fails, check if the md5 command exists.
If that fails as well, cancel the build script. Otherwise, assign the
alias as before.
Aikar
Kyle Wood
ShelLuser
Zach Brown
Mark Vainomaa