cmake: Add FFmpeg/x264 include header path suffix

This allows people to use the base directory of cross-compiled
dependencies (typically our dependencies.zip file), rather than always
having to specify the actual include directory.

cmake/Modules/FindFFmpeg.cmake

@@ -49,7 +49,7 @@ function(find_ffmpeg_library component header)
 			${DepsPath${_lib_suffix}}
 			${DepsPath}
 			${PC_FFMPEG_${component}_INCLUDE_DIRS}
-		PATH_SUFFIXES ffmpeg libav)
+		PATH_SUFFIXES ffmpeg libav include)
 
 	find_library(FFMPEG_${component}_LIBRARY
 		NAMES

cmake/Modules/FindLibx264.cmake

@@ -32,7 +32,9 @@ find_path(X264_INCLUDE_DIR
 		${DepsPath}
 		${_X264_INCLUDE_DIRS}
 	PATHS
-		/usr/include /usr/local/include /opt/local/include /sw/include)
+		/usr/include /usr/local/include /opt/local/include /sw/include
+	PATH_SUFFIXES
+		include)
 
 find_library(X264_LIB
 	NAMES ${_X264_LIBRARIES} x264 libx264