devel/libgee: fix build with clang 16

Clang 16 has a new error about incompatible function types, which shows
up when building devel/libgee:

  hashmap.c:4089:23: error: incompatible function pointer types assigning to 'gboolean (*)(GeeMapIterator *)' (aka 'int (*)(struct _GeeMapIterator *)') from 'gboolean (GeeHashMapNodeIterator *)' (aka 'int (struct _GeeHashMapNodeIterator *)') [-Wincompatible-function-pointer-types]
          iface->get_read_only = gee_hash_map_map_iterator_real_get_read_only;
                               ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Since the error occurs in vala-generated code, it does not make sense to
patch the .c file. Suppress the warning instead.

PR:		271485
Approved by:	maintainer timeout (2 weeks)
MFH:		2023Q2

devel/libgee/Makefile

 PORTNAME=	libgee
 PORTVERSION=	0.20.6
+PORTREVISION=	1
 CATEGORIES=	devel
 MASTER_SITES=	GNOME
 DIST_SUBDIR=	gnome
@@ -15,10 +16,16 @@ PORTSCOUT=	limitw:1,even
 
 GNU_CONFIGURE=	yes
 CONFIGURE_ARGS=	--enable-introspection=yes
-USES=		cpe gettext gmake gnome libtool pathfix pkgconfig tar:xz vala:build
+USES=		compiler cpe gettext gmake gnome libtool pathfix pkgconfig tar:xz vala:build
 USE_GNOME=	glib20 introspection:build
 USE_LDCONFIG=	yes
 INSTALL_TARGET=	install-strip
 CPE_VENDOR=	gnome
 
-.include <bsd.port.mk>
+.include <bsd.port.pre.mk>
+
+.if ${COMPILER_TYPE} == clang
+CFLAGS+=	-Wno-incompatible-function-pointer-types
+.endif
+
+.include <bsd.port.post.mk>