Add -boundscheck=[on|safeonly|off] option

Replaces -noboundscheck (which becomes deprecated)

Fixes issue #12550
Cleanup -vgc implementation
Merge pull request #3405 from jpf91/cleanVGC

Cleanup -vgc implementation
Merge pull request #3443 from eco/boundscheck

Add -boundscheck=[on|safeonly|off] option