I have custom libevent location: /usr/local/libevent
./configure script does not add -I/usr/local/libevent/include to makefiles

If --I is enforced by "CCFLAG" variable everything compiles cleanly

my "configure"
./configure \
--prefix=/usr/local/zabbix \
--sysconfdir=/usr/local/etc/zabbix/ \
\
--enable-server \
--enable-proxy \
--enable-agent \
\
--with-mysql=/usr/local/mysql/bin/mysql_config \
--with-libxml2=/usr/local/libxml2/bin/xml2-config \
--with-net-snmp=/usr/local/net-snmp/bin/net-snmp-config \
--with-openssl=/usr/local/openssl \
--with-libcurl=/usr/local/curl/bin/curl-config \
--with-ssh2=/usr/local/libssh2 \
--with-ldap=/usr/local/openldap \
--with-libevent=/usr/local/libevent \

output ("server" section")
Enable server: yes
Server details:
With database: MySQL
WEB Monitoring: cURL
Native Jabber: no
SNMP: yes
IPMI: no
SSH: yes
TLS: OpenSSL
ODBC: no
Linker flags: -L/usr/local/mysql/lib -L/usr/local/libxml2/lib -L/usr/local/net-snmp/lib -L/usr/local/libssh2/lib -L/usr/local/libevent/lib -L/usr/local/openssl/lib -L/usr/local/openldap/lib -L/usr/local/curl/lib -rdynamic -L/usr/local/pcre/lib
Libraries: -lmysqlclient -lxml2 -lnetsnmp -lssh2 -levent -lssl -lcrypto -lldap -llber -lcurl -lm -ldl -lresolv -lpcreposix -lpcre

and "make" command results:
Making all in src
make[1]: Entering directory '/usr/local/src/zabbix/zabbix-3.4.0rc1/src'
Making all in libs
make[2]: Entering directory '/usr/local/src/zabbix/zabbix-3.4.0rc1/src/libs'
Making all in zbxcrypto
make[3]: Entering directory '/usr/local/src/zabbix/zabbix-3.4.0rc1/src/libs/zbxcrypto'
gcc -DHAVE_CONFIG_H -I. -I../../../include -I/usr/local/openssl/include -I/usr/local/curl/include -O2 -I/usr/local/pcre/include -MT libzbxcrypto_a-md5.o -MD -MP -MF .deps/libzbxcrypto_a-md5.Tpo -c -o libzbxcrypto_a-md5.o `test -f 'md5.c' || echo './'`md5.c
In file included from ../../../include/common.h:23:0,
from md5.c:54:
../../../include/sysinc.h:425:20: fatal error: event.h: No such file or directory

1. include <event.h>