neon: add license
neon: add license

From README.md:

    The neon library source code is licensed under the GNU Library GPL;
    see src/COPYING.LIB for full details.

Headers in src state:

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

mfikes/homebrew-core,JCount/homebrew-core,adam-moss/homebrew-core,Linuxbrew/homebrew-core,mbcoguno/homebrew-core,mbcoguno/homebrew-core,mbcoguno/homebrew-core,cblecker/homebrew-core,sjackman/homebrew-core,cblecker/homebrew-core,chrisfinazzo/homebrew-core,zyedidia/homebrew-core,lemzwerg/homebrew-core,chrisfinazzo/homebrew-core,Moisan/homebrew-core,Linuxbrew/homebrew-core,mfikes/homebrew-core,uyjulian/homebrew-core,Homebrew/homebrew-core,makigumo/homebrew-core,JCount/homebrew-core,Moisan/homebrew-core,filcab/homebrew-core,stgraber/homebrew-core,Homebrew/homebrew-core,lemzwerg/homebrew-core,uyjulian/homebrew-core,nandub/homebrew-core,zyedidia/homebrew-core,nbari/homebrew-core,nandub/homebrew-core,adam-moss/homebrew-core,sjackman/homebrew-core,nbari/homebrew-core,filcab/homebrew-core,makigumo/homebrew-core,stgraber/homebrew-core