Extensible main thread stack is tricky :(.

Revision 14976 causes a regression : stacktrace produced when the
stack has not yet been extended to cover SP will only contain one
element, as the stack limits are considered to be the limits of
the resvn segment.

This patch fixes that, by taking Resvn/SmUpper segment into
account to properly compute the limits.
It also contains a new regtest that fails with the trunk
(only one function in the stacktrace)
and succeeds with this patch (the 2 expected functions).

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15046 a5019735-40e9-0310-863c-91ae7b9d1cf9
5 files changed