debian: fix package configuration after removing platform_defs.h.in

debian: fix package configuration after removing platform_defs.h.in

In commit 0fa9dcb61b4f, we made platform_defs.h a static header file
instead of generating it from platform_defs.h.in.  Unfortunately, it
turns out that the debian packaging rules use "make
include/platform_defs.h" to run configure with the build options
set via LOCAL_CONFIGURE_OPTIONS.

Since platform_defs.h is no longer generated, the make command in
debian/rules does nothing, which means that the binaries don't get built
the way the packaging scripts specify.  This breaks multiarch for
libhandle.so, as well as libeditline and libblkid support for
xfs_db/io/spaceman.

Fix this by correcting debian/rules to make include/builddefs, which
will start ./configure with the desired options.

Fixes: 0fa9dcb61b4f ("include: stop generating platform_defs.h")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>