The vmm module currently combines parts of the kernelspace
getrlimit(2) machinery and a sysctl value to limit the number
of VMM instances per-UID. The original rationale for this
approach was to sidestep the convoluted way in which per-UID
getrlimit(2) limit values are currently propagated.
However, this approach deviates from the expected workflow when dealing
getrlimit(2) limits.
Fix this by teaching login(1) about RLIMIT_VMM and changing
vmmdev_create to use lim_cur. While we're here, document the limit
in the getrlimit(2) manpage.
Fixes: 1092ec8b3375 ("kern: Introduce RLIMIT_VMM")