kbuild: print short log in addition to the whole command with V=1

"make V=1" prints the whole command instead of the short log, but I
think it is nicer to print both so that you can easily spot the build
rule of your interest.

This commit changes V=1 to print the short log (the line starts with
'#'), followed by the full log.

In parallel builds, the short/full logs from the same build rule may
be interspersed. If you want to avoid it, please add -Otarget option.
Kbuild will never set it by default because Make would buffer the logs
and lose the escape sequences. (Modern compilers print warnings and
errors in color, but only when they write to a terminal.)

This is also a preparation for supporting V=12 because V=2 appends the
reason for rebuilding to the short log.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>