package/jack2: add host-pkgconf dependency

Fix the following build failure raised since commit
69284b6700e5f45e25a583e87b86ed1eb95038fd:

Checking for program 'pkg-config'        : not found
The above check failed, but the checkee is required for --alsa.

Indeed, before this commit, host-pkgconf was pulled by libsndfile
dependency

Fixes:
 - http://autobuild.buildroot.org/results/cbdc251980f5571f75281202ebffc04ddecbf28d

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 4e9d04986e6545e9258a8ba925c4538e6a9a481a)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/jack2/jack2.mk

@@ -9,7 +9,7 @@ JACK2_SITE = $(call github,jackaudio,jack2,v$(JACK2_VERSION))
 JACK2_LICENSE = GPL-2.0+ (jack server), LGPL-2.1+ (jack library)
 JACK2_LICENSE_FILES = COPYING
 JACK2_CPE_ID_VENDOR = jackaudio
-JACK2_DEPENDENCIES = alsa-lib
+JACK2_DEPENDENCIES = host-pkgconf alsa-lib
 JACK2_INSTALL_STAGING = YES
 
 JACK2_CONF_OPTS = --alsa --example-tools=no