RLIMIT_DATA (ulimit -d) if RLIMIT_DATA is not 0 (unlimited).
If RLIMIT_DATA is 0 then the default 512MB reservation will be used.
Using 32MB made v8 use less memory for sure but it was a huge performance
loss too.
- pull across a patch from www/chromium to use the same memory allocation
policy on amd64 as is currently used on i386, this seriously reduces the
amount of virtual memory required