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>

scripts/package/debian/rules

@@ -11,6 +11,14 @@ ifneq (,$(filter-out parallel=1,$(filter parallel=%,$(DEB_BUILD_OPTIONS))))
     MAKEFLAGS += -j$(NUMJOBS)
 endif
 
+# When KBUILD_VERBOSE is undefined (presumably you are directly working with
+# the debianized tree), show verbose logs unless DEB_BUILD_OPTION=terse is set.
+ifeq ($(origin KBUILD_VERBOSE),undefined)
+    ifeq (,$(filter terse,$(DEB_BUILD_OPTIONS)))
+        export KBUILD_VERBOSE := 1
+    endif
+endif
+
 revision = $(lastword $(subst -, ,$(shell dpkg-parsechangelog -S Version)))
 CROSS_COMPILE ?= $(filter-out $(DEB_BUILD_GNU_TYPE)-, $(DEB_HOST_GNU_TYPE)-)
 make-opts = ARCH=$(ARCH) KERNELRELEASE=$(KERNELRELEASE) KBUILD_BUILD_VERSION=$(revision) $(addprefix CROSS_COMPILE=,$(CROSS_COMPILE))