package/trousers: needs host-pkgconf

Otherwise the build fail with this error:
configure.in:53: error: possibly undefined macro: AC_MSG_ERROR
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.
configure.in:95: error: possibly undefined macro: AM_CONDITIONAL

Also, there is a PKG_CHECK_MODULES used for GTK.

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/trousers/trousers.mk

@@ -12,7 +12,7 @@ TROUSERS_LICENSE_FILES = LICENSE
 TROUSERS_INSTALL_STAGING = YES
 # Need autoreconf because of a patch touching configure.in and Makefile.am
 TROUSERS_AUTORECONF = YES
-TROUSERS_DEPENDENCIES = openssl
+TROUSERS_DEPENDENCIES = host-pkgconf openssl
 
 ifeq ($(BR2_PACKAGE_LIBICONV),y)
 TROUSERS_DEPENDENCIES += libiconv