Hello,
so far no luck with building. Here is verbose tail fragment;

: "toolchain/musl/prepare.. "
rm -rf /home/im/openadk/toolchain_build_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/w-musl-git-1
mkdir -p /home/im/openadk/toolchain_build_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/w-musl-git-1
touch /home/im/openadk/toolchain_build_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/w-musl-git-1/.checksum_done
PATH='/home/im/openadk/scripts:/home/im/openadk/toolchain_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/usr/bin:/home/im/openadk/host_x86_64-linux-gnu/usr/bin:/home/im/openadk/host_x86_64-linux-gnu/usr/sbin:/home/im/openadk/host_x86_64-linux-gnu/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin'; mkdir -p /home/im/openadk/toolchain_build_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/w-musl-git-1; cd /home/im/openadk/toolchain_build_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/w-musl-git-1 && for file in /home/im/openadk/dl/musl-git.tar.xz; do case $file in *.cpio) cat $file | cpio -i -d ;; *.tar) tar -xf $file ;; *.cpio.Z | *.cpio.gz | *.cgz | *.mcz) gzip -dc $file | cpio -i -d ;; *.tar.xz | *.txz) xz -dc $file | tar -xf - ;; *.tar.Z | *.tar.gz | *.taz | *.tgz) gzip -dc $file | tar -xf - ;; *.cpio.bz2 | *.cbz) bzip2 -dc $file | cpio -i -d ;; *.tar.bz2 | *.tbz | *.tbz2) bzip2 -dc $file | tar -xf - ;; *.tar.lz | *.tlz) lzip -dc $file | tar -xf - ;; *.zip) unzip -d /home/im/openadk/toolchain_build_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/w-musl-git-1 $file ;; *.arm|*.jar|*.ids.gz) mkdir /home/im/openadk/toolchain_build_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/w-musl-git-1/musl-git; cp $file /home/im/openadk/toolchain_build_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/w-musl-git-1/musl-git ;; *.bin) sh $file --force --auto-accept ;; *) echo "Cannot extract '$file'" >&2; false ;; esac; done
make[6]: Nothing to be done for 'post-extract'.
touch /home/im/openadk/toolchain_build_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/w-musl-git-1/musl-git/.extract_done
[ ! -d ./patches/git ] || PATH='/home/im/openadk/scripts:/home/im/openadk/toolchain_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/usr/bin:/home/im/openadk/host_x86_64-linux-gnu/usr/bin:/home/im/openadk/host_x86_64-linux-gnu/usr/sbin:/home/im/openadk/host_x86_64-linux-gnu/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin' /bin/bash /home/im/openadk/scripts/patch.sh /home/im/openadk/toolchain_build_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/w-musl-git-1/musl-git ./patches/git \
'{patch-!(*.orig),*.patch,*.arm,*.musl}'

Applying ./patches/git/s390-hotfix.patch using plaintext:
patching file src/signal/s390x/sigsetjmp.s
Reversed (or previously applied) patch detected! Assume -R? [n]
Apply anyway? [n]
Skipping patch.
1 out of 1 hunk ignored -- saving rejects to file src/signal/s390x/sigsetjmp.s.rej
Aborting. Reject files found.
/home/im/openadk/mk/buildhlp.mk:77: recipe for target '/home/im/openadk/toolchain_build_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/w-musl-git-1/musl-git/.prepared' failed
make[5]: *** [/home/im/openadk/toolchain_build_raspberry-pi0_musl_arm1176jzf_s_hard_eabihf/w-musl-git-1/musl-git/.prepared] Error 1
Makefile:92: recipe for target 'musl-prepare' failed
make[4]: *** [musl-prepare] Error 2
mk/build.mk:221: recipe for target 'toolchain/final' failed
make[3]: *** [toolchain/final] Error 2
/home/im/openadk/mk/build.mk:170: recipe for target 'world' failed
make[2]: *** [world] Error 2