Debugger: Do not try to treat labels as variables

They produce no values later anyway and are slow to process.
With this patch, stepping in VME::run from qv4vme_moth.cpp
takes about 1s instead of more than 40s previously.

Change-Id: I5c96966612bdb7c0120d9ebb545d6e8483cbf843
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>

share/qtcreator/debugger/gdbbridge.py

@@ -290,6 +290,9 @@ class Dumper(DumperBase):
                 warn("UNEXPECTED 'None' BLOCK")
                 break
             for symbol in block:
+
+              # Filter out labels etc.
+              if symbol.is_variable or symbol.is_argument:
                 name = symbol.print_name
 
                 if name == "__in_chrg" or name == "__PRETTY_FUNCTION__":