package/linux-tools: change method for including linux-tool sub-makefiles

package/linux-tools: change method for including linux-tool sub-makefiles

Make inclusion ordering of all linux-tool-*.mk sub-makefiles explicit
instead of relying on alphabetical sort order. This is done by
renaming the Linux tools sub-makefiles to the format linux-tool-*.mk.in.
This causes the top-level Makefile to ignore the Linux tools
sub-makefiles.

Until now, the main Makefile included all linux-tool-*.mk files, as
well as linux-tools.mk, and it relied on alphabetical sorting to
include them in the proper order (linux-tool-*.mk before
linux-tools.mk).

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
[Thomas: improve comment in the code as suggested by Yann.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>