misc/cgo/testcshared: increase sleep in TestUnexportedSymbols

Increase the sleep and wait for up to 2 seconds for the dup2.
Apparently it can sometimes take a long time.

Fixes #23784

Change-Id: I929530b057bbcd842b28a7640c39dd68d719ff7d
Reviewed-on: https://go-review.googlesource.com/93895
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

misc/cgo/testcshared/main2.c

@@ -21,7 +21,7 @@ int main(void) {
 
   // The descriptor will be initialized in a thread, so we have to
   // give a chance to get opened.
-  for (i = 0; i < 1000; i++) {
+  for (i = 0; i < 200; i++) {
     n = read(fd, buf, sizeof buf);
     if (n >= 0)
       break;
@@ -33,7 +33,7 @@ int main(void) {
     // An EBADF error means that the shared library has not opened the
     // descriptor yet.
     ts.tv_sec = 0;
-    ts.tv_nsec = 1000000;
+    ts.tv_nsec = 10000000;
     nanosleep(&ts, NULL);
   }