This is in preparation for adding handling of (Ada) task-specific
breakpoints in this routine.  I could have just modified the condition
inside the loop, but it was getting too nested for my taste, making
the condition hard to read.  So here's a cleanup that would provide
two improvements: readability, and computing of the ptid's thread-id
in a lazy way.  Most of the time, at least for myself, I don't use
thread-specific breakpoints, so might as well not compute the thread ID.

Reference: http://www.sourceware.org/ml/gdb-patches/2009-03/msg00551.html

2009-03-25  Joel Brobecker  <brobecker@adacore.com>

        * breakpoint.c (breakpoint_thread_match): Split a large condition
        into several smaller conditions.  No behavior change.

Tested on x86_64-linux. I made this change in a pretty procedural and
mechanical way.  But a second pair of eyes would be appreciated. Plus,
I'd like to know if others also prefer splitting this condition like
I did.

Thanks,
-- 
Joel