Makefile: unconditionally include pkg-utils.mk

Currently, pkg-utils.mk (included via package/Makefile.in) is only included
when a configuration file already exists. This means that none of the
utilities it defines are available without .config.

In particular:
- the MESSAGE macro, causing pretty build output. Since some make targets
  can be run even without .config, like 'make manual', not having this
  pretty printing is odd.

- pkgname, pkgdir: in a subsequent patch, these functions will be used for
  the generation of the manual, and since this should work also without
  .config, we need these functions to be available.

This patch moves the include of pkg-utils.mk from package/Makefile.in to
Makefile, outside of the check for .config.

This is a quick fix. The full solution involves to minimize the amount of
Makefile code that is guarded by a check on .config. This approach will be
taken in the 2014.11 release cycle.

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Reviewed-by: Samuel Martin <s.martin49@gmail.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>