android: fix detection of pthread_condattr_setclock

It's only available on API level >= 21.

PR-URL: https://github.com/libuv/libuv/pull/1441
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

src/unix/thread.c

@@ -528,7 +528,7 @@ int uv_cond_init(uv_cond_t* cond) {
   if (err)
     return -err;
 
-#if !(defined(__ANDROID__) && defined(HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC))
+#if !(defined(__ANDROID_API__) && __ANDROID_API__ < 21)
   err = pthread_condattr_setclock(&attr, CLOCK_MONOTONIC);
   if (err)
     goto error2;