classes/insane: add check for PN in OVERRIDES

classes/insane: add check for PN in OVERRIDES

If a recipe is named such that its PN value matches something already in
OVERRIDES (such as when PN happens to be the same as MACHINE or DISTRO),
it can have unexpected consequences. Assignments such as
FILES_${PN} = "xyz" effectively turn into FILES = "xyz".

Implements [YOCTO #4288].

(From OE-Core rev: c331f0a5cac765174a1b5de5c12aec7e965d4158)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>