little bug with the new python prompt stuff, the prompt_hook doesn't
take effect until the second prompt.

I couldn't for the life of me figure out how to do a testcase for this...
using gdb.mi/mi-async.exp as an example of using -ex it still didn't
want to work,
there was also the need to match the very first prompt.
and command line python stuff seems to go awry of how skip_python_tests works.
sorry.

before:
gdb/gdb -quiet -ex 'set prompt (foo) ' -ex 'python def prompt(x):
return "(bar) "' -ex 'python gdb.prompt_hook = prompt'
(foo)
(bar) quit

~/git/gdb/gdb/gdb -quiet -ex 'python def prompt(x): return "(bar) "'
-ex 'python gdb.prompt_hook = prompt'
(gdb)
(bar) quit


after:
gdb/gdb -quiet -ex 'set prompt (foo) ' -ex 'python def prompt(x):
return "(bar) "' -ex 'python gdb.prompt_hook = prompt'
(bar)
(bar) quit

gdb/gdb -quiet -ex 'python def prompt(x): return "(bar) "' -ex 'python
gdb.prompt_hook = prompt'
(bar)
(bar) quit

ran the above things with --enable-tui --disable-tui plus gdb --interpreter=tui
and ran the testsuite with --enable-tui and --disable-tui.
didn't see anything but what looked like tests that fail randomly.

I think it's ok anyways, the 'if (async_command_editing_p)' case in
display_gdb_prompt seems to cover it,
with the addition of rl_callback_handler_remove() which afaict seemed
ok to call before a handler is installed

otherwise, there is a workaround
calling gdb.execute("set prompt " + prompt("foo"))

Thanks.

2011-07-30  Matt Rice  <ratmice@gmail.com>

        * event-top.c (cli_command_loop): Remove code redundant to
        display_gdb_prompt.
        * tui/tui-interp.c (tui_command_loop): Ditto.