Implement command line option --valgrind-stacksize=<number>

This allows to decrease memory usage when using many threads,
if no big stacksize is needed by Valgrind.
If needed (e.g. for demangling big c++ symbols), the V stacksize
can be increased.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15004 a5019735-40e9-0310-863c-91ae7b9d1cf9
11 files changed