[PATCH v7 0/7] Remote fork events

[Don Breazeal <donb@codesourcery.com>]

This is v7 of the patch series implementing remote follow-fork, last
posted here: https://sourceware.org/ml/gdb-patches/2015-03/msg00503.html

This patchset only implements fork and vfork events for extended remote,
omitting exec events and 'target remote' for now.

Changes from the previous version:

 * Patch 1: removed documentation portion, putting it in a separate
            documentation patch (patch 7).

 * Patch 3: addressed a number of review comments.  The significant
            changes include:
	    - temporarily pause all lwps when gdb (re)connects, in
	      order to set the ptrace options.
	    - rework the mechanism for setting ptrace options.
	    - refactor remote_detach_1 per review comments.
	    - removed a test change (will submit it as a separate patch).
	    - moved documentation changes to doc patch #7.

 * Patch 5: changed a couple a spots to address how gdbserver checks
	    whether fork events have been requested by gdb and whether they
	    are enabled.  Also moved documentation changes to doc patch #7.

 * Patch 6: significant changes include:
            - changed method of removing fork child threads from the
	      thread list reported from the remote target, prior to
	      follow_fork.
	    - changed how gdb determines whether a process that is
	       to be killed contains a fork parent thread
	    - removed a test change that isn't needed for this patchset.
	    - moved documentation changes to doc patch #7.
	    
* Patch 7: new patch that incorporates all doc changes for the patchset.

The patch descriptions are mostly unchanged except for the new patch:

1/6: Preparatory patch that implements qSupported support for fork events
     and associated mechanisms.

     Previously approved minus doc portions here:
     https://sourceware.org/ml/gdb-patches/2015-03/msg00896.html

2/6: Implements functions to clone breakpoint lists in gdbserver.

     Previously approved pending a few 'nits', fixes are documented here:
     https://sourceware.org/ml/gdb-patches/2014-10/msg00883.html.

3/6: Implements follow fork for 'fork' but not 'vfork', for
     extended-remote targets only.

4/6: Adds the architecture-specific pieces of follow-fork that allows
     hardware watchpoints to be inherited by a forked child.

     Previously approved here:
     https://sourceware.org/ml/gdb-patches/2015-02/msg00262.html

5/6: Adds follow fork for 'vfork'.

6/6: Adds catchpoints for 'fork' and 'vfork', along with support for
     killing a process that has forked before follow_fork is completed.

7/7: Documentation for the patch series.

TESTING:
Testing was mostly done using x86_64 Ubuntu, with the exception of the
architecture-specific patch, #4.  There are a few failures that show up
but don't signify any problem.

 - Intermediate patches show failures due to the lack of features
   implemented in subsequent patches, like missing hardware watchpoint
   or catchpoint support.

 - Some vfork tests fail due to the lack of exec event support.

Thanks,
--Don