tools/libs: Fix build dependencies

tools/libs: Fix build dependencies

Some libs' Makefile aren't loading the dependencies files *.d2.

We can load them from "libs.mk" as none of the Makefile here are
changing $(DEPS) or $(DEPS_INCLUDE) so it is fine to move the
"include" to "libs.mk".

As a little improvement, don't load the dependencies files (and thus
avoid regenerating the *.d2 files) during `make clean`.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>