test: increase upper bound in condvar_5

Problem:
Upper bound on thread wakeup was set to 1.5 * (requested timeout).
On MacOS wakeup delay factors of 1.75 have been reported.

Solution:
Increase the bound to 5 * (requested timeout).

Refs: https://github.com/libuv/libuv/issues/1910
PR-URL: https://github.com/libuv/libuv/pull/1990
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>

test/test-condvar.c

@@ -259,7 +259,7 @@ TEST_IMPL(condvar_5) {
    * https://msdn.microsoft.com/en-us/library/ms687069(VS.85).aspx */
   elapsed = after - before;
   ASSERT(0.75 * timeout <= elapsed); /* 1.0 too large for Windows. */
-  ASSERT(elapsed <= 1.5 * timeout); /* 1.1 too small for OSX. */
+  ASSERT(elapsed <= 5.0 * timeout); /* MacOS has reported failures up to 1.75. */
 
   worker_config_destroy(&wc);