BUILD: makefile: Fix building with closefrom() support enabled

BUILD: makefile: Fix building with closefrom() support enabled

I noticed the USE_CLOSEFROM define was not being passed along like the rest
during the build.

Looking around I see this was broken with the following two commits and related
series..

BUILD: Makefile: also report disabled options in the BUILD_OPTIONS variable
http://git.haproxy.org/?p=haproxy.git;a=commit;h=05fd82da76d1bbc8d65d63ab246bda7cbcf8481a

BUILD: pass all "USE_*" variables as -DUSE_* to the compiler
http://git.haproxy.org/?p=haproxy.git;a=commit;h=824cd00d3bda8f7f6d4c30baf77ba6c19ab47811

Looks like this should be back ported to 2.0, 2.1 and 2.2.