src: use g_fsync for portability

The g_fsync() API provides the same Windows portability
as GNULIB does for fsync().
Reviewed-by: NFabiano Fidêncio <fidencio@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

src/nwfilter/nwfilter_dhcpsnoop.c

@@ -1772,7 +1772,7 @@ virNWFilterSnoopLeaseFileWrite(int lfd, const char *ifkey,
         goto cleanup;
     }
 
-    ignore_value(fsync(lfd));
+    ignore_value(g_fsync(lfd));
 
  cleanup:
     VIR_FREE(lbuf);

src/storage/storage_util.c

@@ -384,7 +384,7 @@ createRawFile(int fd, virStorageVolDefPtr vol,
         }
     }
 
-    if (fsync(fd) < 0) {
+    if (g_fsync(fd) < 0) {
         ret = -errno;
         virReportSystemError(errno, _("cannot sync data to file '%s'"),
                              vol->target.path);

src/util/virfile.c

@@ -519,7 +519,7 @@ virFileRewrite(const char *path,
         goto cleanup;
     }
 
-    if (fsync(fd) < 0) {
+    if (g_fsync(fd) < 0) {
         virReportSystemError(errno, _("cannot sync file '%s'"),
                              newfile);
         goto cleanup;