ProcessStub: Add missing if

When not starting in debug mode, the inferior is not waiting
for ptrace(DETACH), so the code that calls DETACH waits for
something that does not happen.

Fixes: QTCREATORBUG-29503
Change-Id: Ic00a52b9e4f3a797d1be337a2ce53afc6ee63927
Reviewed-by: Cristian Adam <cristian.adam@qt.io>

src/tools/process_stub/main.cpp

@@ -222,6 +222,7 @@ void onInferiorStarted()
     if (!debugMode)
         sendPid(inferiorId);
 #else
+    if (debugMode) {
         qCInfo(log) << "Detaching ...";
         ptrace(PTRACE_DETACH, inferiorId, 0, SIGSTOP);
 
@@ -238,6 +239,7 @@ void onInferiorStarted()
             else if (WIFCONTINUED(status))
                 qCInfo(log) << "inferior continued";
         }
+    }
 
     sendPid(inferiorId);
 #endif