add pkg-config to the build environment

alpine/Dockerfile.builder

@@ -5,7 +5,7 @@ RUN echo "Prepare base image filelist" \
     && export OS_FILELIST=/tmp/os_filelist \
     && find /  \( -path /etc -o -path /dev -o -path /home -o -path /media -o -path /proc -o -path /mnt -o -path /root -o -path /sys -o -path /tmp -o -path /run \) -prune  -o -print >> ${OS_FILELIST} \
     && echo "Preparing build environment" \
-    && apk add --no-cache abuild git gcc build-base bison db-dev gawk flex expat-dev perl-dev postgresql-dev python3-dev pcre2-dev mariadb-dev \
+    && apk add --no-cache abuild git gcc build-base pkgconfig bison db-dev gawk flex expat-dev perl-dev postgresql-dev python3-dev pcre2-dev mariadb-dev \
          libxml2-dev curl-dev unixodbc-dev confuse-dev ncurses-dev sqlite-dev lua-dev openldap-dev \
          net-snmp-dev libuuid libev-dev jansson-dev json-c-dev libevent-dev linux-headers \
          libmemcached-dev rabbitmq-c-dev hiredis-dev libmaxminddb-dev libunistring-dev freeradius-client-dev lksctp-tools-dev ruby-dev \