util: Remove unnecessary check in virFileRewrite

Since g_strdup_printf will abort, we know @newfile won't be NULL.

Found by Coverity
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>

src/util/virfile.c

@@ -543,8 +543,7 @@ virFileRewrite(const char *path,
 
  cleanup:
     VIR_FORCE_CLOSE(fd);
-    if (newfile)
-        unlink(newfile);
+    unlink(newfile);
     return ret;
 }