Here is the updated diff with sthen's feedback. It adds a gssapi flavor for openldap.
Index: Makefile =================================================================== RCS file: /cvs/ports/databases/openldap/Makefile,v retrieving revision 1.148 diff -u -p -r1.148 Makefile --- Makefile 17 Dec 2016 14:11:21 -0000 1.148 +++ Makefile 18 May 2017 22:21:10 -0000 @@ -10,10 +10,6 @@ PKGNAME-main = ${DISTNAME:S/-/-client-/ PKGNAME-server = ${DISTNAME:S/-/-server-/} REVISION = 3 -# overwrite -main pkgname/path to strip FLAVOR, aci only affects the server -FULLPKGNAME-main = ${DISTNAME:S/-/-client-/} -FULLPKGPATH-main = databases/openldap,-main - SHARED_LIBS += lber 12.0 # 12.6 SHARED_LIBS += lber-2.4 12.0 @@ -49,7 +45,7 @@ CONFIGURE_STYLE = autoconf USE_GROFF = Yes FLAVOR ?= -FLAVORS = aci +FLAVORS = aci gssapi CONFIGURE_ARGS += --enable-ipv6 \ --with-tls=openssl @@ -92,6 +88,18 @@ CONFIGURE_ARGS += --disable-mdb .if ${FLAVOR:Maci} CONFIGURE_ARGS += --enable-aci + +# overwrite -main pkgname/path to strip FLAVOR, aci only affects the server +FULLPKGNAME-main = ${DISTNAME:S/-/-client-/}${FLAVOR_EXT:S/-aci//} +FULLPKGPATH-main = databases/openldap,-main${FLAVOR_EXT:S/-aci//:S/-/,/g} +.endif + +.if ${FLAVOR:Mgssapi} +CONFIGURE_ARGS += --enable-gssapi=${LOCALBASE}/heimdal +MODULES += security/heimdal +WANTLIB += heimdal/lib/gssapi +WANTLIB += heimdal/lib/heimntlm +WANTLIB += heimdal/lib/heimsqlite .endif MODGNU_CONFIG_GUESS_DIRS = ${WRKSRC} ${WRKSRC}/build