The binary-arch target needs to use the same CROSS_COMPILE as used in
build-arch; otherwise, 'make run-command' may attempt to resync the
.config file.

Squash scripts/package/deb-build-option into debian/rules, as it is a
small amount of code.

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

Commit 3ab18a625ce4 ("kbuild: deb-pkg: improve the usability of source
package") set needless CROSS_COMPILE.

For example, 'make allnoconfig bindeb-pkg' on a x86_64 system will set
CROSS_COMPILE=i686-linux-gnu-, where the biarch compiler 'gcc' should
work for building the i386 kernel.

  $ uname -m
  x86_64
  $ make allnoconfig bindeb-pkg >/dev/null
  dpkg-architecture: warning: specified GNU system type i686-linux-gnu does not match CC system type x86_64-linux-gnu, try setting a correct CC environment variable
   dpkg-source --before-build .
   debian/rules binary
  scripts/Kconfig.include:39: C compiler 'i686-linux-gnu-gcc' not found
  make[6]: *** [scripts/kconfig/Makefile:77: olddefconfig] Error 1
  make[5]: *** [Makefile:693: olddefconfig] Error 2
  make[4]: *** [Makefile:358: __build_one_by_one] Error 2
  make[3]: *** [debian/rules:7: build-arch] Error 2
  dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2
  make[2]: *** [scripts/Makefile.package:127: bindeb-pkg] Error 2
  make[1]: *** [Makefile:1657: bindeb-pkg] Error 2
  make: *** [Makefile:358: __build_one_by_one] Error 2

Check whether CROSS_COMPILE is defined, instead of whether it is non-empty.

If you invoke debian/rules via Kbuild, CROSS_COMPILE is always defined
in the top Makefile.

Fixes: 3ab18a625ce4 ("kbuild: deb-pkg: improve the usability of source package")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

KERNELRELEASE does not need to match the package version in changelog.
Rather, it conventially matches what is called 'ABINAME', which is a
part of the binary package names.

Both are the same by default, but the former might be overridden by
KDEB_PKGVERSION. In this case, the resulting package would not boot
because /lib/modules/$(uname -r) does not point the module directory.

Partially revert 3ab18a625ce4 ("kbuild: deb-pkg: improve the usability
of source package").

Reported-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Fixes: 3ab18a625ce4 ("kbuild: deb-pkg: improve the usability of source package")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>

Improve the source package support in case the dpkg-buildpackage is
directly used to build binary packages.

For cross-compiling, you can set CROSS_COMPILE via the environment
variable, but it is better to set it automatically - set it to
${DEB_HOST_GNU_TYPE}- if we are cross-compiling but not from the top
Makefile.

The generated source package may be carried to a different build
environment, which may have a different compiler installed.
Run olddefconfig first to set new CONFIG options to their default
values without prompting.

Take KERNELRELEASE and KBUILD_BUILD_VERSION from the version field of
debian/changelog in case it is updated afterwards.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>