DR nanosleep syscall fails > 3 times leading to assert

Following assertion fires occasionally when running test client.mangle_suspend (version 38239008)

if (count++ > 3 && !IS_CLIENT_THREAD(get_thread_private_dcontext())) { ASSERT_NOT_REACHED(); break; /* paranoid */ }

To reproduce more reliably, change nanosleep timeout in suite/tests/client-interface/mangle_suspend.c:71 to

 /* Pick an uneven number to maximize the number of suspend calls w/o                                                                                                                                           
 * running into limitations in DR.                                                                                                                                                                             
 */
sleeptime.tv_nsec = 100 * 1111