Utils: Add the ability to interrupt inferiors via the process stub

This will be handy once we want to debug processes running as root.

The mechanism is the same as for "killProcess", and currently unused.

Change-Id: I2c5e5b77577ca32ed1118fcc81c03c6320db8800
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

src/libs/utils/consoleprocess.cpp

@@ -604,6 +604,18 @@ bool ConsoleProcess::start()
     return true;
 }
 
+void ConsoleProcess::interruptProcess()
+{
+#ifdef Q_OS_WIN
+    // Not used.
+#else
+    if (d->m_stubSocket && d->m_stubSocket->isWritable()) {
+        d->m_stubSocket->write("i", 1);
+        d->m_stubSocket->flush();
+    }
+#endif
+}
+
 void ConsoleProcess::killProcess()
 {
 #ifdef Q_OS_WIN