This is an idea to make "thread step-in --target" work for the common

case where you have:

1 ->    foo (bar(),
2            baz(),
3            lala());
4

You are sitting on line 1, and want to step into foo, but not bar, baz & lala.  Unfortunately
there are line table entries for lines 1-3, and lldb doesn't know anything about the nesting
of statement in these lines.  So we'll have to use the user's intelligence...  This patch adds:

(lldb) thread step-in -t foo --end-line 4

That tells lldb to keep stepping in till line 4, but stop if you step into foo.  I think I would
remember to use this when faced with some of the long gnarly call sequences in lldb.  But there
might be ways I haven't thought of to make it more convenient.  Jason suggests having "end" as a
special token for --end-line which just means keep going to the end of the function, I really want
to get into this thing...

There should be an SB API and tests, which will come if this seems useful.

llvm-svn: 260352