[arch-releng] Update needed to releng scripts

[Gerardo Exequiel Pozzi]

Hello Dieter

I want some coordination with you to merge my dm-snapshot branch in 
master (archiso) so you can change releng scripts.

Detailed manually build steps are here [#1]

If you need more info please let me know.

Basically the changes are (from build view):

---- Single ISOs ----
* Deprecated configs/syslinux-iso in favour to configs/releng
* configs/releng uses a bash script instead of make
* Equivalence of commands is:

     make net-iso -> ./build.sh net_iso_single
     make core-iso -> ./build.sh core_iso_single
     make [all] -> ./build.sh all_iso_single
     make clean -> ./build.sh clean_single

* Note: Like with previous method, after building "core", if you build 
"netinstall" you get a "core" iso called "netinstall". (TODO: I need to 
fix this in a easy way)
* Important: inside the chroot you need one loopback device available (@1)

---- Dual ISOs ----
* Deprecated archiso2dual script in favour of configs/releng/build.sh
* While archiso2dual use *.iso images, build.sh use the result of 
./build.sh *_iso_single commands, in other words join 
${work_dir}/${arch}/iso (via hardlinks).
* No more profiles (single, split, full), since the work of profile 
"split" is now done for single images.
* build.sh accept these commands for doing dual images.

     ./build.sh net_iso_dual
     ./build.sh core_iso_dual
     ./build.sh all_iso_dual
     ./build.sh clean_dual

* These commands does not trigger the build of single images. You need 
to do it before.
* No issues if execute first "core" then "netinstall" (I managed it in 
this case)
* No loopback device is needed for this step.


(@1) Create one, for example "mknod /dev/loop1032 b 7 1032" for 32 bit 
chroot and loop1064 for 64 bits (of course this will work only if loop 
module is loaded without any parameters that limit the number of loop 
devices or set number of partitions).

[#1] https://wiki.archlinux.org/index.php/User:Djgera#archiso

-- 
Gerardo Exequiel Pozzi
\cos^2\alpha + \sin^2\alpha = 1