porting: include compat-errno.h for errno's

disperse module fails to compile since
ENODATA is non-existent on FreeBSD/Darwin

Use errno conversion in compat-errno.h to avoid
build issues.

Change-Id: I0126224f06365e0b8fac16c205f1294863dc2bc4
BUG: 1111774
Signed-off-by: Harshavardhana <harsha@harshavardhana.net>
Reviewed-on: http://review.gluster.org/8350
Tested-by: Gluster Build System <jenkins@build.gluster.com>