This is definitely one of the ugliest things I ever got my
hands on. If it even did the job properly, but no, it tries
to install it's headers in /usr/include/curl collidings with
actual curl's headers. Fixed that by installing them into
/usr/include/gnurl instead. Now gnunet can use gnurl.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>