Callgrind: fix bug 217849: Switch to running thread in CLG_(post_signal)

If instrumentation is switched off on multithreaded code,
multiple signals in a row handled by different threads could
confuse callgrind.
Callgrind assumed that in post_signal, it has the correct understanding
of the currently running thread. This is not always correct.
Really switch to running thread.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@10966 a5019735-40e9-0310-863c-91ae7b9d1cf9
1 file changed