msgpack lib missed using lua_checkstack and so on rare
cases overflow the stack by at most 2 elements. This is a
violation of the Lua C API. Notice that Lua allocates
additional 5 more elements on top of lua->stack_last
so Redis does not access an invalid memory. But it is an
API violation and we should avoid it.
This PR also added a new Lua compilation option. The new
option can be enable using environment variable called
LUA_DEBUG. If set to `yes` (by default `no`), Lua will be
compiled without optimizations and with debug symbols (`-O0 -g`).
In addition, in this new mode, Lua will be compiled with the
`-DLUA_USE_APICHECK` flag that enables extended Lua C API
validations.
In addition, set LUA_DEBUG=yes on daily valgrind flow so we
will be able to catch Lua C API violations in the future.
a8c1253b6f