manibuilder: Refresh DJGPP image

Replace the unmaintained anibali/djgpp image with a Debian-based image
that installs the current prebuilt DJGPP GCC 12.2.0 toolchain.

The old container depended on flashprog.org artifact downloads for a
pciutils patch and libgetopt tarball. Those URLs are gone, so build
against pciutils 3.15.0 directly and use the public getopt 2.5 tarball.

Update the manibuilder DJGPP tag and build documentation accordingly.

Tested:
- podman run ... getopt configure && make
- make -C util/manibuilder show-working
- make -C util/manibuilder -n 'djgpp:12.2.0-build'

Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Change-Id: If39a15012dc83b1a2b33e0824b1c44646a6a6964
Reviewed-on: https://review.sourcearcade.org/c/flashprog/+/520
Tested-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/util/manibuilder/Makefile b/util/manibuilder/Makefile
index a9be1fe..b5a35f8 100644
--- a/util/manibuilder/Makefile
+++ b/util/manibuilder/Makefile
@@ -52,7 +52,7 @@
 $(foreach tag,$(OFFICIAL_TAGS), \
 	$(eval $(call build_template,$(tag),$(tag),$(call official_stem,$(tag)),$(call official_plat,$(tag)))))
 
-djgpp\:6.1.0-build: %-build: Dockerfile.djgpp mani-wrapper.sh
+djgpp\:12.2.0-build: %-build: Dockerfile.djgpp mani-wrapper.sh
 	$(QUIET_SETUP)docker build . -f $< -t mani/$* --build-arg IDENT=$(call ident,$*)
 
 source-build: Dockerfile.source