Enable some syscalls to resume after SIGPROF

Summary: Add the SA_RESTART flag when registering the SIGPROF handler to allow some system calls to be resumed if interrupted by SIGPROF. For example, the hermes CLI tool would not work propertly after enabling the sampling profiler as the interrupt handler would cause the read() calls to fail.

Reviewed By: kodafb

Differential Revision: D33594168

fbshipit-source-id: 5c52676aec9316635f343606d7d3012a42249249

Author: jpporto

lib/VM/Profiler/SamplingProfilerPosix.cpp

@@ -76,7 +76,8 @@ int SamplingProfiler::GlobalProfiler::invokeSignalAction(void (*handler)(int)) {
   struct sigaction actions;
   memset(&actions, 0, sizeof(actions));
   sigemptyset(&actions.sa_mask);
-  actions.sa_flags = 0;
+  // Allows interrupted IO primitives to restart.
+  actions.sa_flags = SA_RESTART;
   actions.sa_handler = handler;
   return sigaction(SIGPROF, &actions, nullptr);
 }