Merge pull request #5059 from Orphis/ffmpeg_windows

cmake: Find bundled ffmpeg even if you have pkg-config on Win32

CMake/CheckLib.cmake

@@ -60,7 +60,9 @@ macro(check_libav)
 	if(PKG_CONFIG_FOUND)
 		pkg_check_modules(LIBAV libavcodec>=54.35.0 libavformat>=54.20.4
 			libswscale>=2.1.1 libavutil>=52.3.0)
-	else()
+	endif()
+
+	if(NOT LIBAV_FOUND)
 		if(WIN32)
 			add_library(avcodec STATIC IMPORTED)
 			set_target_properties(avcodec PROPERTIES
@@ -114,6 +116,7 @@ macro(check_libav)
 			unset(CMAKE_REQUIRED_LIBRARIES)
 	  endif()
 	endif()
+
 	if(LIBAV_FOUND)
 		message(STATUS "libav/ffmpeg found, enabling AVI frame dumps")
 		add_definitions(-DHAVE_LIBAV)