python: Remove unused readline import

The readline module is imported by main.py but doesn't seem to be
used.

Change-Id: I7888e3b6ad0a0fedc14b0feec2adf0a39883bbf8
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/3421
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

src/python/m5/main.py

@@ -410,10 +410,6 @@ def main(*args):
     scope = { '__file__' : filename,
               '__name__' : '__m5_main__' }
 
-    # we want readline if we're doing anything interactive
-    if options.interactive or options.pdb:
-        exec "import readline" in scope
-
     # if pdb was requested, execfile the thing under pdb, otherwise,
     # just do the execfile normally
     if options.pdb: