In handle_inferior_event() when stepping over a watch point currently we
issue target_resume().  This only works on architectures that have
hardware single step support.  For gdbarch_software_single_step_p()
systems (like MIPS), we need to insert a single step breakpoint instead.

The fix is to call resume() as it does the right thing already.  I also
added an assert that inferior_ptid == ecs->ptid to be sure that resume()
was stepping the proper thread.

This is essentially the change requested by Daniel in:
http://sourceware.org/ml/gdb-patches/2008-04/msg00443.html

This change is a prerequisite for my forthcoming MIPS hardware watch patch.

Tested on x86_64-pc-linux-gnu as well as mipsel-linux (in conjunction
with the MIPS hardware watch patch).

OK to commit?

2008-09-09  David Daney  <ddaney@avtrex.com>

	* infrun.c (handle_inferior_event): Call resume instead of
	target_resume when stepping over watchpoint.