After [1] in upstream LLVM, ld.lld's version output became slightly
different when the cmake configuration option LLVM_APPEND_VC_REV is
disabled.

Before:

  Debian LLD 19.0.0 (compatible with GNU linkers)

After:

  Debian LLD 19.0.0, compatible with GNU linkers

This results in ld-version.sh failing with

  scripts/ld-version.sh: 18: arithmetic expression: expecting EOF: "10000 * 19 + 100 * 0 + 0,"

because the trailing comma is included in the patch level part of the
expression. While [1] has been partially reverted in [2] to avoid this
breakage (as it impacts the configuration stage and it is present in all
LTS branches), it would be good to make ld-version.sh more robust
against such miniscule changes like this one.

Use POSIX shell parameter expansion [3] to remove the largest suffix
after just numbers and periods, replacing of the current removal of
everything after a hyphen. ld-version.sh continues to work for a number
of distributions (Arch Linux, Debian, and Fedora) and the kernel.org
toolchains and no longer errors on a version of ld.lld with [1].

Fixes: 02aff859 ("kbuild: check the minimum linker version in Kconfig")
Link: https://github.com/llvm/llvm-project/commit/0f9fbbb63cfcd2069441aa2ebef622c9716f8dbb [1]
Link: https://github.com/llvm/llvm-project/commit/649cdfc4b6781a350dfc87d9b2a4b5a4c3395909 [2]
Link: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html [3]
Suggested-by: Fangrui Song <maskray@google.com>
Reviewed-by: Fangrui Song <maskray@google.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>