Merge patch series "Update kbuild"

Ilias Apalodimas <ilias.apalodimas@linaro.org> says:

Last time the kbuild scripts were synced with the Linux kernel was on the
4.20 release. Updating directly to 6.x makes the diff difficult to read, so
let's do the changes incrementally and bump to 5.1 first.

Since the number of commits is big, I am splitting this in multiple series.
This one includes most of the commits for Makefile.build,
Makefile.lib and some from Makefile.

commit eeb5687a7139649e ("kbuild: add -Werror=strict-prototypes flag unconditionally")
commit 3812b8c5c5d5 ("kbuild: make -r/-R effective in top Makefile for old Make versions")
commit b421b8a6cb87 ("kbuild: remove unused archmrproper")
commit 1a49b2fd8f58 ("kbuild: strip whitespace in cmd_record_mcount findstring")
commit 88110713ca9dfb ("kbuild: hardcode genksyms path and remove GENKSYMS variable")
commit 1d8001ef358 ("kbuild: generate modules.order only when CONFIG_MODULES=y")
commit 45c4372d00 ("kbuild: refactor quiet_modtag")
commit b39a691617e4 commit ("kbuild: remove redundant quiet_modtag for $(obj-m)")
commit 5439f09f488f ("kbuild: remove redundant 'set -e' from cmd_* defines")
commit e5d289100d3a ("kbuild: remove trailing semicolon from cmd_* passed to if_changed_rule")
commit 3a2429e1faf4 ("kbuild: change if_changed_rule for multi-line recipe")
commit ee3e46b7efd2 ("kbuild: refactor modversions build rules")
commit 4317ee3b6a5e ("kbuild: remove redundant 'set -e' from sub_cmd_record_mcount")
commit 392885ee82d3 ("kbuild: let fixdep directly write to .*.cmd files")
commit 898f5a009f22 ("kbuild: move archive command to scripts/Makefile.lib")
commit b79c6aa6a1f1 ("kbuild: remove unnecessary in-subshell execution")
commit afa974b77128 ("kbuild: add real-prereqs shorthand for $(filter-out FORCE,$^)")
commit ecbd10d90e94 ("kbuild: simplify rules of data compression with size appending")
commit 58156ba4468f ("kbuild: skip 'addtree' and 'flags' magic for external module build")
commit 172caf1993b7 ("kbuild: remove redundant target cleaning on failure")
commit f3fd4a3f3a38 ("kbuild: remove redundant 'set -e' from filechk_offsets")
commit a2237fec1e06 ("kbuild: Enable dtc graph_port warning by default")
commit 70523a3ce5ff ("kbuild: disable dtc simple_bus_reg warnings by default")
commit e4aca4595005 ("kbuild: de-duplicate fixdep usage")

Link: https://lore.kernel.org/r/20250520052153.307194-1-ilias.apalodimas@linaro.org

diff --cc Makefile
Simple merge

diff --cc scripts/Makefile.lib
Simple merge