Add sleep to posix library startup to avoid race. Closes #857

* On win32 we can get the target control port instantly and immediately connect
  before program startup, on posix systems we must wait until afterwards and
  poll for open sockets.
* This means there's a small window of opportunity where the program may have
  started running but we haven't connected yet to send any initial commands.
  Adding a sleep should give target control time to connect.

renderdoc/os/posix/posix_libentry.cpp

@@ -69,6 +69,10 @@ void library_loaded()
     RDCLOG("Loading into %s", curfile.c_str());
 
     LibraryHooks::RegisterHooks();
+
+    // we have a short sleep here to allow target control to connect, since unlike windows we can't
+    // suspend the process during startup.
+    Threading::Sleep(15);
   }
 }