Currently the linux-source-<version> package may or may not include
these files, depending on the order things are built in.
As autotools always modifies the source directory, copy (rsync) the
source to the build directory and build in-place there.
Some years back I patched the #include of <linux/usbip.h> to include
the current, uninstalled version through a relative path because the
system-installed version will normally be outdated. We're about to
start copying the source to avoid writing autotools crap into the
source directory, which breaks this relative path.
Since we now install the UAPI headers under debian/build at the start
of the tools build, drop the patch and add that directory to the
include path.
Pass $(CROSS_COMPILE) or host GNU type through to upstream build rules.
debian/rules.real: Filter tools packages by host arch, not build arch
debian/rules.d/Makefile: Build the tools needed for headers_install in
a separate subdirectory
By passing both -C and -f options to make, we can separate makefiles
from the output directory without adding prefixes to all targets.
We can also reduce the 'clean' commands to little more than 'rm -rf'.
Ben Hutchings