Process record and replay checked in to main trunk

[Hui Zhu <teawater@gmail.com>]

Hi guys,

Process record and replay make gdb can record inferior execute log and
replay (include reverse debug).
Now, it support I386-Linux single-thread single-inferior native debug.


It was checked in today.
Thanks for evey people that spent time on process record.  Precord
can't be a part of gdb without your help.  Thank you very much.  :)


And precord still has a long way to go.  There have a lot of thing need to do:

1. Support i386 more better.  Now, precord doesn't support mmx insns,
support fp insns not very well and doesn't support a lot of insns.

2. Support more arches.  X86-64 is the first one (linux-record.c).
MIPS, ARM and so on.

3. Support memory free better.  Now, precord just can output a warning
for memumap.  It can do nothing when there is a sys_brk to free the
memory.
I had make a patch to output a warning when there is a sys_brk to free
the memory and make a plan to make precord can support free memory.
I will keep work on it.

4. Support multi-thread and multi-inferior.
I remember Pedro make a patch for reverse debug resume.  I think we
need this patch when multi-inferior check in.

5. Make record speed up and need less memory.
I have made a plan to make p record doesn't record execution log of
some functions (It can set), for example some functions in glibc.

6. Make execution log can dump out to be a file and can replay for next time.
Maybe it can make together with coredump support.  It must be a cool
function.  :)

Guys, please work on it if you interesting with some of them.  And
feel free tell me your ideas and comments.  It will help precord a
lot.


Thanks,
Hui