same as the global variable defined in ip_input.c. Instead, adopt the name
'q' as found in about 1/2 of uses in ip_input.c, preventing a collision on
the name. This is non-harmful, but means that search and replace on the
global works less well (as in the virtualization work), as well as indexing
tools.
MFC after: 1 week
Reported by: julian
37f44cb428