dht: Avoid using inline, if necessary use it with 'static inline'

This avoids flat namespace problems on OSX and with clang

Change-Id: Id80d94d71b120c6b1166218caa8cf9cf7f2da03a
BUG: 1130888
Signed-off-by: Harshavardhana <harsha@harshavardhana.net>
Reviewed-on: http://review.gluster.org/8547
Tested-by: Gluster Build System <jenkins@build.gluster.com>