Make some vgdb interface to callgrind_control internal

The vgdb "status" monitor command is still available, but
used for pretty printing of status information now (acutally,
just some place holder for real information up to now: just
number of running threads). The internal interface used by
callgrind_control to provide stack traces and event counts
is using "status internal", and is not documented, as the
format is not for human consumption.

This also adds some documentation.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@12014 a5019735-40e9-0310-863c-91ae7b9d1cf9
3 files changed