Drop PRIORITY variable

As discussed on the mailing list, this variable isn't useful and if wanted
would be better implemented by distros using pn-X overrides.

This patch executes:

find . -regex ".*\.\(bb\|inc\)$" | xargs sed -i '/^PRIORITY = ".*"$/d'

against the tree removing the referenced. Thanks to Phil Blundell for
the command.

(From OE-Core rev: d122343362669c683acc4af295971a62cbc823fc)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/python/python.inc

@@ -2,7 +2,6 @@ DESCRIPTION = "The Python Programming Language"
 HOMEPAGE = "http://www.python.org"
 LICENSE = "PSF"
 SECTION = "devel/python"
-PRIORITY = "optional"
 # bump this on every change in contrib/python/generate-manifest-2.6.py
 INC_PR = "nk2"