Fallback to old FindFFMpeg script when pkg-config fails.

This should work better on Windows, hopefully. It worked well
enough when I intentionally broke pkg-config, anyway.

CMakeLists.txt

@@ -149,7 +149,10 @@ ENDIF(ENABLE_SOUND)
 ENDIF ()
 
 IF(ENABLE_LIBAVCODEC)
-	pkg_check_modules(FFMPEG REQUIRED libavcodec)
+	pkg_check_modules(FFMPEG libavcodec)
+	IF(NOT(FFMPEG_FOUND))
+		INCLUDE(FindFFMpeg REQUIRED)
+	ENDIF(NOT(FFMPEG_FOUND))
 	# Compatibility checks for ffmpeg deprecated functions
 	INCLUDE(CheckFunctionExists REQUIRED)
 	SET(CMAKE_REQUIRED_FLAGS ${LIBAVCODEC_CFLAGS})

conf/FindFFMpeg.cmake

@@ -0,0 +1,33 @@
+# - Find libavcodec (FFMPEG)
+# Find the native FFMPEG headers and libraries.
+# Only grabs what Lightspark needs currently
+#
+#  FFMPEG_INCLUDE_DIRS - where to find avcodec.h
+#  FFMPEG_LIBRARIES    - List of libraries when using ffmpeg
+#  FFMPEG_FOUND        - True if ffmpeg found.
+
+# Look for the header file.
+FIND_PATH(FFMPEG_INCLUDE_DIR NAMES libavcodec/avcodec.h PATH_SUFFIXES ffmpeg)
+MARK_AS_ADVANCED(FFMPEG_INCLUDE_DIR)
+
+# Look for the library.
+FIND_LIBRARY(FFMPEG_AVCODEC_LIBRARY NAMES 
+    avcodec
+)
+
+FIND_LIBRARY(FFMPEG_AVUTIL_LIBRARY NAMES
+    avutil
+)
+
+SET(FFMPEG_LIBRARY ${FFMPEG_AVCODEC_LIBRARY} ${FFMPEG_AVUTIL_LIBRARY})
+MARK_AS_ADVANCED(FFMPEG_LIBRARY)
+
+# handle the QUIETLY and REQUIRED arguments and set FFMPEG_FOUND to TRUE if 
+# all listed variables are TRUE
+INCLUDE(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(FFMPEG DEFAULT_MSG FFMPEG_LIBRARY FFMPEG_INCLUDE_DIR)
+
+IF(FFMPEG_FOUND)
+  SET(FFMPEG_LIBRARIES ${FFMPEG_LIBRARY})
+  SET(FFMPEG_INCLUDE_DIRS ${FFMPEG_INCLUDE_DIR})
+ENDIF(FFMPEG_FOUND)