Fix assert in gdbserver for watchpoints watching the same address

GDB can create watchpoints watching the same address.
This was causing assertion failures.
To handle this, hash table (with key watched address) is replaced
by an xarray of address/lengh/kind.
Fully identical watches are ignored (either not inserted, and
not causing a problem if already deleted).

gdbserver_tests/mcwatchpoint enhanced to test duplicated watchpoints



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@12637 a5019735-40e9-0310-863c-91ae7b9d1cf9
4 files changed