kern.{post,pre}.mk: Clean up a bit.
kern.post.mk:
-------------
* eddep is not used in kernel context.
* linterrs and the lint target should have been removed when I removed
xlint back in 84f800532904979799aaeb8123487026f76a6640.
* setdef[01].c and setdefs.h should have been removed when gensetdefs
was removed in 5e0107f67f7c659007103f791401be27957081cf.
kern.pre.mk:
------------
* Remove some old FreeBSD inherited code that we don't need to build
a kernel without /usr/src.
* While here, Remove unneeded quotation marks around two include
directories.
UnifiedSplitRaw
