[PATCH v4 0/4] tools/build: Allow versioning of all LLVM tools

I ran into the build issue mentioned in the first commit, because using
an option like LLVM=-15 is a documented way to build [1], but only
some of the LLVM tools defined in tools/ support this.

After fixing that, a lot of other tidyups fell out. I didn't go too far,
for example some selftests include tools/testing/selftests/lib.mk which
reimplements some of the LLVM_SUFFIX stuff, but other selftests include
tools/scripts/Makefile.include and I stopped before touching the former.
Some other non build scripts hard code toolchains and I didn't touch
those either, this change is only focused on things that already
include Makefile.include.

[1]: Documentation/kbuild/llvm.rst

Signed-off-by: James Clark <[email protected]>
---
Changes in v4:
- Drop "tools/build: selftests: Allow versioning LLVM lld", clang
  already picks the correct sibling lld version. (Sashiko)
- Link to v3: https://lore.kernel.org/r/[email protected]

Changes in v3:
- Add warning for empty $USE_LD
- Use $HOSTREADELF in bpf Makefile
- Rebase on v7.2-rc3
- Link to v2: https://lore.kernel.org/r/[email protected]

Changes in v2:
- Fix selftests/bpf build. LLD needs to take the full path to be used
  with -fuse-ld=
- Link to v1: https://lore.kernel.org/r/[email protected]

---
James Clark (4):
      tools/build: Allow versioning of all LLVM tools defined in Makefile.include
      tools/build: Indent if else blocks
      tools/build: Allow versioning LLVM readelf
      tools/build: selftests: Remove some duplicate toolchain definitions

 tools/bpf/resolve_btfids/Makefile    |  3 --
 tools/lib/api/Makefile               |  4 --
 tools/lib/bpf/Makefile               |  8 ++--
 tools/lib/subcmd/Makefile            |  4 --
 tools/lib/symbol/Makefile            |  4 --
 tools/perf/Makefile.perf             |  7 ----
 tools/scripts/Makefile.include       | 77 ++++++++++++++++++++----------------
 tools/testing/selftests/bpf/Makefile |  1 -
 8 files changed, 46 insertions(+), 62 deletions(-)
---
base-commit: a13c140cc289c0b7b3770bce5b3ad42ab35074aa
change-id: 20260511-james-perf-llvm-version-43ab1cb5bc7d

Best regards,
-- 
James Clark <[email protected]>