graphics/qgis: Readd patch to fix flex version

For FreeBSD versions < 1300501 the existing version of FLEX in base is
unsufficient. Readd old patch to install the ports version of FLEX.

CMake Error at /usr/local/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:230
  (message): Could NOT find FLEX: Found unsuitable version "2.5.37",
  but required is at least "2.6" (found /usr/bin/flex)
Call Stack (most recent call first):
  /usr/local/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:598
    (_FPHSA_FAILURE_MESSAGE)
  /usr/local/share/cmake/Modules/FindFLEX.cmake:269
    (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
  CMakeLists.txt:339 (find_package)

Thanks to Martin Birgmeier <d8zNeCFG@aon.at> for reporting.

PR:		274793

graphics/qgis/Makefile

@@ -1,5 +1,6 @@
 PORTNAME=	qgis
 DISTVERSION=	3.34.0
+PORTREVISION=	1
 CATEGORIES=	graphics geography
 MASTER_SITES=	https://qgis.org/downloads/
 
@@ -157,6 +158,13 @@ SERVER_CMAKE_BOOL=	WITH_SERVER WITH_SERVER_PLUGINS WITH_QSPATIALITE
 
 .include <bsd.port.pre.mk>
 
+# QGIS requires flex >= 2.5.6, see
+# https://github.com/qgis/QGIS/blob/fb0f334b06e0828e5695ffcaa7c7eb82d6516cb0/INSTALL.md
+.if (${OPSYS} == FreeBSD && ${OSVERSION} < 1300501)
+BUILD_DEPENDS+=	${LOCALBASE}/bin/flex:textproc/flex
+CMAKE_ARGS+=	-DFLEX_EXECUTABLE:FILEPATH=${LOCALBASE}/bin/flex
+.endif
+
 pre-patch:
 	# Only PostgreSQL Client headers, not Server
 	@${REINPLACE_CMD} -e 's|set(POSTGRES_INCLUDE_DIR \$${PostgreSQL_INCLUDE_DIRS})|set(POSTGRES_INCLUDE ${LOCALBASE}/include)|g' \