cross-avr-gcc15-bootstrap-15.1.1+git9973-160000.2.2

- Fixup conflicts again.
- Make sure to retain binary suffixes for accelerator crosses.

- Update to GCC 15 branch head, 15.1.1+git9973
- Fixes PR120995, unrecognizable insn UNSPEC_COMPARE_AND_SWAP with
  rv64gc_zabha_zacas

- Prune the use of update-alternatives from openSUSE Factory and
  SLFO.
- Adjust crosses to conflict consistently where they did not
  already and make them use unsuffixed binaries.

- Tune for power10 for SLES 16.  [jsc#PED-12029]
- Tune for z15 for SLES 16.  [jsc#PED-253]

- Update to GCC 15 branch head, 15.1.1+git9866
- Fix PR120827, ICE due to splitter emitting constant loads directly

- Remove all %gcc_icecream mode cross-compilers and the corresponding
  icecream backend subpackages.  Instead use glibc-bootstrap only
  configs for cross-x86_64-gcc (ipxe,ovmf,qemu), cross-ppc64-gcc (qemu)
  and cross-arm-gcc (ovmf).

- Revert pruning the set of cross-compilers that conflict with different
  versions from the set using update-alternatives.  This causes
  endless headache with file conflicts with older GCC releases.

- Exclude shared objects present for link editing in the GCC specific
  subdirectory from provides processing via __provides_exclude_from.
  [bsc#1244050][bsc#1243991]

- Make cross-*-gcc15-bootstrap package conflict with the non-bootstrap
  variant conflict with the unversioned cross-*-gcc package.

- Enable C++ for offload compilers.  [bsc#1243794]