* ggc-common.c (ggc_rlimit_bound): Don't check RSS limit.
Check DATA limit only if there's no AS limit. Ignore insanely
low DATA limits.
(ggc_min_heapsize_heuristic): Don't divide AS or RSS limits by 8,
but take care that the AS limit isn't overrun.
* doc/invoke.texi: Update documentation of min-heapsize parameter.