debugger: disable "threadnames"

This works around the problem that the threadnames deduction switches
the current thread and thereby invalidates the assumption that the
thread mentioned in the *stopped response is the "current" thread.

There's already a proper fix in master including some performance
enhancements.

Reviewed-by: con

share/qtcreator/gdbmacros/dumper.py

@@ -94,6 +94,7 @@ def isGoodGdb():
     return 'parse_and_eval' in __builtin__.dir(gdb)
 
 def hasInferiorThreadList():
+    return False
     try:
         a= gdb.inferiors()[0].threads()
         return True