add support for overlay directories by using PKGCATEGORY

[dinoex]

Problem:

poudriere check for sane CATEGORIES fails on ports using custom PKGCATEGORY

Example:

mkdir /usr/ports/local
echo "PKGCATEGORY=local" > /usr/ports/local/Makefile.inc
echo "PKGNAMESUFFIX?=-local" >> /usr/ports/local/Makefile.inc
rsync -a /usr/ports/ports-mgmt/dialog4ports/ /usr/ports/local/dialog4ports/
echo "local/dialog4ports" > ~/pkglist
poudriere ports -c
poudriere jail -c -v 14.0-RELEASE -a i386 -j 14i386
poudriere bulk -f ~/pkglist -j 14i386

Logs:

[00:00:00] Creating the reference jail... done
[00:00:00] Mounting system devices for 14i386-default
[00:00:00] Mounting ports/packages/distfiles
[00:00:00] Using packages from previously failed build: /pbuild14/data/packages/14i386-default/.building
[00:00:00] Mounting packages from: /pbuild14/data/packages/14i386-default
[00:00:00] Appending to make.conf: /usr/local/etc/poudriere.d/make.conf
/etc/resolv.conf -> /pbuild14/data/.m/14i386-default/ref/etc/resolv.conf
[00:00:00] Starting jail 14i386-default
[00:00:00] Will build as nobody: (65534:65534)
[00:00:01] Logs: /pbuild14/data/logs/bulk/14i386-default/2023-11-27_07h53m38s
[00:00:01] Loading MOVED for /pbuild14/data/.m/14i386-default/ref/usr/ports
[00:00:01] Ports supports: FLAVORS SELECTED_OPTIONS
[00:00:01] Gathering ports metadata
[00:00:01] Warning: (local/dialog4ports): Error: local/dialog4ports has incorrect CATEGORIES, first should be 'local'.  Please contact maintainer of the port to fix this.
[00:00:01] Error: Fatal errors encountered gathering ports metadata 
[00:00:01] Cleaning up
14i386-default: removed
14i386-default-n: removed
[00:00:01] Unmounting file systems

Diagnostics:

in bsd.port.mk the origin of a port is defined by PKGCATEGORY PKGORIGIN?= ${PKGCATEGORY}/${PORTDIRNAME}

which defaults to the first entry in CATEGORIES: PKGCATEGORY?= ${_CATEGORY}

The Ports system handles such overlay pretty well. This was used by others as well, for example by portrookies.

This patch solves the problem for me.