BNCSUtil: Statically link BNCSUtil to aura-bot.

With this change we have no more .dll files to keep in the tree and we
get a simple aura.exe file to distribute.
bncsutil: Fix compilation on other-than-Windows platforms.
Makefile: Remove libgmp linking in aura-bot.
Aura-bot itself doesn't link to gmp, bncsutil does.
Merge branch 'master' of https://github.com/Josko/aura-bot
Reflect recent upstream changes