terminal adapter: make skipping of initial SIGSTOPs more reliable

first, _start being resolvable depends on libc-dbg being installed.
second, depending on the frame being in the dynloader makes it
a) work only for dynamic executables and b) fail on multi-target
systems (due to a hard-coded file name).
so instead just remember the entry point, as we are already there
anyway.

Reviewed-By: hjk

src/plugins/debugger/gdb/termgdbadapter.cpp

@@ -119,6 +119,9 @@ void TermGdbAdapter::handleStubAttached(const GdbResponse &response)
         setState(InferiorStopped);
         debugMessage(_("INFERIOR ATTACHED"));
         emit inferiorPrepared();
+#ifdef Q_OS_LINUX
+        m_engine->postCommand(_("-stack-list-frames 0 0"), CB(handleEntryPoint));
+#endif
     } else if (response.resultClass == GdbResultError) {
         QString msg = _(response.data.findChild("msg").data());
         emit inferiorStartFailed(msg);
@@ -130,6 +133,17 @@ void TermGdbAdapter::startInferiorPhase2()
     m_engine->continueInferiorInternal();
 }
 
+#ifdef Q_OS_LINUX
+void TermGdbAdapter::handleEntryPoint(const GdbResponse &response)
+{
+    if (response.resultClass == GdbResultDone) {
+        GdbMi stack = response.data.findChild("stack");
+        if (stack.isValid() && stack.childCount() == 1)
+            m_engine->m_entryPoint = stack.childAt(0).findChild("addr").data();
+    }
+}
+#endif
+
 void TermGdbAdapter::interruptInferior()
 {
     const qint64 attachedPID = m_engine->inferiorPid();