RHEL/CentOS 7, popular distributions that install GNU Make 3.82, reached
EOM/EOL on June 30, 2024. While you may get extended support, it is a
good time to raise the minimum GNU Make version.

The new requirement, GNU Make 4.0, was released in October, 2013.

I did not touch the Makefiles under tools/ because I do not know the
requirements for building tools. I do not find any GNU Make version
checks under tools/.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>