games/openmw: Move to FFmpeg 4

Move to FFmpeg 4 due to dependency of graphics/osg

Approved by:	portmgr (blanket, build fix)
Sponsored by:	Blinkinblox

games/openmw/Makefile

@@ -11,7 +11,7 @@ WWW=		https://openmw.org/
 LICENSE=	GPLv3
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
-LIB_DEPENDS=	libavcodec.so:multimedia/ffmpeg \
+LIB_DEPENDS=	libavcodec.so.58:multimedia/ffmpeg4 \
 		libboost_thread.so:devel/boost-libs \
 		libMyGUIEngine.so:x11-toolkits/mygui \
 		libBulletCollision.so:devel/bullet@double \
@@ -44,6 +44,9 @@ DOCS_USES=		python:build
 
 PORTDOCS=	*
 
+post-patch:
+	@${REINPLACE_CMD} -e 's|%%LOCALBASE%%|${LOCALBASE}|g' \
+		${PATCH_WRKSRC}/cmake/FindFFmpeg.cmake
 post-install:
 	@${STRIP_CMD} ${STAGEDIR}${PREFIX}/bin/*
 

games/openmw/files/patch-cmake_FindFFmpeg.cmake

@@ -0,0 +1,11 @@
+--- cmake/FindFFmpeg.cmake.orig	2023-04-24 10:57:53 UTC
++++ cmake/FindFFmpeg.cmake
+@@ -33,6 +33,8 @@
+ # Redistribution and use is allowed according to the terms of the BSD license.
+ # For details see the accompanying COPYING-CMAKE-SCRIPTS file.
+
++set(CMAKE_PREFIX_PATH "%%LOCALBASE%%/ffmpeg4;%%LOCALBASE%%/ffmpeg4/libexec")
++
+ include(LibFindMacros)
+ include(FindPackageHandleStandardArgs)
+