kbuild: deb-pkg: show verbose log for direct package builds

kbuild: deb-pkg: show verbose log for direct package builds

When the Debian package build is initiated by Kbuild ('make deb-pkg'
or 'make bindeb-pkg'), the log messages are displayed in the short
form, which is the Kbuild default.

Otherwise, let's show verbose messages (unless the 'terse' tag is set
in DEB_BUILD_OPTION), as suggested by Debian Policy: "The package build
should be as verbose as reasonably possible, except where the terse tag
is included in DEB_BUILD_OPTIONS." [1]

This is what the Debian kernel also does. [2]

[1]: https://www.debian.org/doc/debian-policy/ch-source.html#main-building-script-debian-rules
[2]: https://salsa.debian.org/kernel-team/linux/-/blob/debian/6.7-1_exp1/debian/rules.real#L36

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <n.schier@avm.de>