Debugger: Skip non-executable auto-detected debuggers

Task-number: QTCREATORBUG-11452

Change-Id: I03a7d2b3dda0b7ffa92ddf1d640d9512f501575e
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/debugger/debuggeritemmanager.cpp

@@ -249,7 +249,7 @@ void DebuggerItemManager::autoDetectGdbOrLldbDebuggers()
     }
 
     foreach (const QFileInfo &fi, suspects) {
-        if (fi.exists()) {
+        if (fi.exists() && fi.isExecutable()) {
             FileName command = FileName::fromString(fi.absoluteFilePath());
             if (findByCommand(command))
                 continue;