test: fix a typo in test-fork.c

PR-URL: https://github.com/libuv/libuv/pull/1721
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>

test/test-fork.c

@@ -335,7 +335,7 @@ TEST_IMPL(fork_signal_to_child_closed) {
     /* Note that we're deliberately not running the loop
      * in the child, and also not closing the loop's handles,
      * so the child default loop can't be cleanly closed.
-     * We need te explicitly exit to avoid an automatic failure
+     * We need to explicitly exit to avoid an automatic failure
      * in that case.
      */
     exit(0);