vi: enable 'dG' command. Closes 11801

vi: enable 'dG' command. Closes 11801

The 'G' command was omitted from the list of commands that change or
delete whole lines.  Add it in the appropriate places so the 'dG',
'cG' and 'yG' commands work, including in cases where an explicit
line number has been supplied.

function                                             old     new   delta
find_range                                           534     596     +62
.rodata                                           175166  175167      +1
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 63/0)               Total: 63 bytes

Reported-by: David Kelly <david.kelly@liberica.ch>
Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>