Change the E1000 driver option header handling to match the
ixgbe driver. As it was, when building them as a module INET
and INET6 are not defined. In these drivers it does not cause
a panic, however it does result in different behavior in the
ioctl routine when you are using a module vs static, and I
think the behavior should be the same.

MFC after: 3 days
Ensure the locale is LC_ALL=C when regenerating src.conf.5

MFC after:	3 days
Disable building of pkg_install by default
If people still want to have pkg_install they can specify WITH_PKGTOOLS when building world
Regenerate src.conf(5) after changing WITHOUT_PKGTOOLS to WITH_PKGTOOLS
Const-ify the new da_delete_functions.
Remove a redundant sanity check

Submitted by:	Steven Hartland
Obtained from:	Netflix
MFC after:	3 days