Fix bashizms

Allow to run utilities like ldd -- substitute variables BASH, KSH, SHELL in configuration with /bin/sh instead of /bin/bash.

Test build in OBS.

Tested APT and OSTree images build and boot for armhf(on SabreLite device) and amd64(QEMU) with this glibc patchset and systemd systemd!53 (merged) (both patchsets are mandotory).

Remove bashisms from test scripts:

• Remove bashisms from test tst-printf-bz18872.sh
• Disabled tst-iconv_prog.sh since it is time consuming to rework it.
• Fix bashizms in tst-syscall-list.sh test script
• Disable tst-ld-sse-use test

Additional build dependency:

• locales-all is fixing test iconv/tst-iconv-opt:

  [ 3192s] FAIL: iconv/tst-iconv-opt
  [ 3192s] original exit status 1
  [ 3192s] error: xsetlocale.c:28: error: setlocale (6, "en_US.UTF-8")