test: fix compiler warnings

Problem:
libuv is compiled with -Wunused-result.
In two tests, read() is used for ordering and the
rc is ignored because it doesn't matter.
But -Wunused-result causes warnings in these cases.

Fix:
Provide a (very generous) check on the rc of read()
in these cases.

PR-URL: #1956
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/test-fork.c

@@ -283,6 +283,7 @@ TEST_IMPL(fork_signal_to_child_closed) {
   int sync_pipe[2];
   int sync_pipe2[2];
   char sync_buf[1];
+  int r;
 
   fork_signal_cb_called = 0;    /* reset */
 
@@ -326,9 +327,10 @@ TEST_IMPL(fork_signal_to_child_closed) {
     /* Don't run the loop. Wait for the parent to call us */
     printf("Waiting on parent in child\n");
     /* Wait for parent. read may fail if the parent tripped an ASSERT
-       and exited, so this isn't in an ASSERT.
+       and exited, so this ASSERT is generous.
     */
-    read(sync_pipe2[0], sync_buf, 1);
+    r = read(sync_pipe2[0], sync_buf, 1);
+    ASSERT(-1 <= r && r <= 1);
     ASSERT(0 == fork_signal_cb_called);
     printf("Exiting child \n");
     /* Note that we're deliberately not running the loop

test/test-pipe-close-stdout-read-stdin.c

@@ -66,7 +66,8 @@ TEST_IMPL(pipe_close_stdout_read_stdin) {
     */
     close(fd[1]);
     /* block until write end of pipe is closed */
-    read(fd[0], &buf, 1);
+    r = read(fd[0], &buf, 1);
+    ASSERT(-1 <= r && r <= 1);
     close(0);
     r = dup(fd[0]);
     ASSERT(r != -1);