lib/Makefile: remove some disabled warnings for lib{fetch,portableproplib}.
lib/Makefile: remove some disabled warnings for lib{fetch,portableproplib}.

There's no need to set _GNU_SOURCE and disable those compiler warning flags.

ebfe/xbps,datenwolf/xbps,ebfe/xbps,stpx/xbps,datenwolf/xbps,stpx/xbps,datenwolf/xbps,stpx/xbps,ebfe/xbps