debian9 64 compilation error

uname -a
Linux debian9-64-2 4.9.0-8-amd64 #1 SMP Debian 4.9.110-3+deb9u4 (2018-08-21) x86_64 GNU/Linux
autoreconf -if && ./configure --enable-shell --with-pgsql --with-mysql --prefix=/home/wlodek/installed/git/

result:

Package:
  Name:              kea
  Version:           1.4.0-git
  Extended version:  1.4.0-git (git 3fc0d776ff2262cae0013de1ce4c776c54c32eba)
  OS Family:         Linux

  Hooks directory:   /home/wlodek/installed/git/lib/hooks
  Premium hooks:     yes
  Included Hooks:    forensic_log flex_id host_cmds subnet_cmds radius host_cache

C++ Compiler:
  CXX:             g++
  CXX_VERSION:     g++ (Debian 6.3.0-18+deb9u1) 6.3.0 20170516
  CXX_STANDARD:    201402
  DEFS:            -DHAVE_CONFIG_H
  CPPFLAGS:         -DOS_LINUX  -DBOOST_ASIO_HEADER_ONLY
  CXXFLAGS:        -g -O2
  LDFLAGS:          -lpthread
  KEA_CXXFLAGS:     -Wall -Wextra -Wnon-virtual-dtor -Wwrite-strings -Woverloaded-virtual -Wno-sign-compare -pthread -Wno-missing-field-initializers -fPIC

Python:
  PYTHON:          /usr/bin/python3
  PYTHON_VERSION:  3.5

Boost:
  BOOST_VERSION:   1.62
  BOOST_INCLUDES:  
  BOOST_LIBS:       -lboost_system

OpenSSL:
  CRYPTO_VERSION:  OpenSSL 1.1.0f  25 May 2017
  CRYPTO_CFLAGS:   
  CRYPTO_INCLUDES: 
  CRYPTO_LDFLAGS:  
  CRYPTO_LIBS:     -lcrypto

Botan: no

Log4cplus:
  LOG4CPLUS_VERSION:  1.1.2
  LOG4CPLUS_INCLUDES: -I/usr/include
  LOG4CPLUS_LIBS:     -L/usr/lib -L/usr/lib64 -llog4cplus

Flex/bison:
  FLEX:  flex
  BISON: bison -y

MySQL:
  MYSQL_VERSION:   10.1.26
  MYSQL_CPPFLAGS:  -I/usr/include/mysql 
  MYSQL_LIBS:      -L/usr/lib/x86_64-linux-gnu  -lmariadbclient -lpthread -lz -lm -ldl

PostgreSQL:
  PGSQL_VERSION:   PostgreSQL 9.6.10
  PGSQL_CPPFLAGS:  -Wdate-time -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -I/usr/include/libxml2 -I/usr/include/tcl8.6 -I/usr/include/postgresql -I/usr/include/postgresql/9.6/server
  PGSQL_LIBS:      -L/usr/lib/x86_64-linux-gnu -lpq

compilation error:

make[6]: Entering directory '/home/wlodek/kea/src/bin/agent'
  CXXLD    kea-ctrl-agent
../../../src/lib/process/.libs/libkea-process.so: undefined reference to `isc::db::DatabaseConnection::toElementDbAccessString(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
collect2: error: ld returned 1 exit status
Makefile:666: recipe for target 'kea-ctrl-agent' failed
make[6]: *** [kea-ctrl-agent] Error 1

It looks like this change:

diff --git a/src/bin/agent/Makefile.am b/src/bin/agent/Makefile.am
index 31a2798d8..75059f357 100644
--- a/src/bin/agent/Makefile.am
+++ b/src/bin/agent/Makefile.am
@@ -83,6 +83,7 @@ kea_ctrl_agent_LDADD += $(top_builddir)/src/lib/log/libkea-log.la
 kea_ctrl_agent_LDADD += $(top_builddir)/src/lib/util/threads/libkea-threads.la
 kea_ctrl_agent_LDADD += $(top_builddir)/src/lib/util/libkea-util.la
 kea_ctrl_agent_LDADD += $(top_builddir)/src/lib/exceptions/libkea-exceptions.la
+kea_ctrl_agent_LDADD += $(top_builddir)/src/lib/database/libkea-database.la
 kea_ctrl_agent_LDADD += $(LOG4CPLUS_LIBS) $(CRYPTO_LIBS) $(BOOST_LIBS)
 
 kea_ctrl_agent_LDFLAGS = $(AM_LDFLAGS) $(CRYPTO_LDFLAGS)

fix issue