evas: improve portability for BSD system.

evas: improve portability for BSD system.

configure: fix prerequisite header issue

Summary:
in some platforms like openBSD <sys/socket.h> must be included before
net/if.h

the canonical way to ensure that with autotools is by providing that
fourth directive.

evas: use MAP_ANON instead of MAP_ANONYMOUS

Stupid unpredictable standards (or not so standard).
MAP_ANON exists and is defined almost anywhere unlike MAP_ANONYMOUS

Let's use that for portability's sake (they are practically identical
anyway)

Reviewers: raster, cedric

Reviewed By: cedric

CC: cedric
Differential Revision: https://phab.enlightenment.org/D616

Signed-off-by: Cedric BAIL <cedric.bail@free.fr>