storage/posix: Fix conditional compiling for syncfs

Change-Id: Ief22e1c0f2b5074060752d70da41ae93f1028d62
BUG: 927146
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/5381
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

xlators/storage/posix/src/posix-helpers.c

@@ -1260,11 +1260,14 @@ posix_fsyncer_syncfs (xlator_t *this, struct list_head *head)
 	*/
 #include <sys/syscall.h>
 #include <unistd.h>
+#ifdef SYS_syncfs
 	syscall (SYS_syncfs, pfd->fd);
 #else
 	sync();
 #endif
-
+#else
+        sync();
+#endif
 }