logging: Added fflush in _gf_log.

Change-Id: I06444b6bc3b1acc8cabd863087bd3508de3c548c
BUG: 889157
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/4344
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>

libglusterfs/src/logging.c

@@ -541,8 +541,10 @@ log:
 
                 if (ctx->log.logfile) {
                         fprintf (ctx->log.logfile, "%s\n", msg);
+                        fflush (ctx->log.logfile);
                 } else {
                         fprintf (stderr, "%s\n", msg);
+                        fflush (stderr);
                 }
 
 #ifdef GF_LINUX_HOST_OS