debugger: don't accept rich text in the gdb startup commands

Task-number: QTCREATORBUG-6771
Change-Id: I9fbb1f275561d9ea422781af3740257235269197
Reviewed-by: hjk <qthjk@ovi.com>

src/plugins/debugger/gdb/gdboptionspage.cpp

@@ -176,7 +176,7 @@ public:
         groupBoxStartupCommands->setTitle(GdbOptionsPage::tr("Additional Startup Commands"));
 
         textEditStartupCommands = new QTextEdit(groupBoxStartupCommands);
-
+        textEditStartupCommands->setAcceptRichText(false);
 
         /*
         groupBoxPluginDebugging = new QGroupBox(q);