pkg-autotools.mk: remove extra space from config-update message

If you do a "make -s", you will notice that the UPDATE_CONFIG_HOOK message
has an extra space compared to other highlighted messages.  For example:

>>> util-linux 2.20.1  Updating config.sub and config.guess
>>> util-linux 2.20.1 Patching libtool
>>> util-linux 2.20.1 Autoreconfiguring

A grep shows this is the only instance of the extra space. This patch
removes the extra space.

Signed-off-by: Danomi Manchego <danomimanchego123@gmail.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>