Add functions to return library license and library configuration.

Originally committed as revision 20547 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavdevice/avdevice.c

@@ -22,3 +22,14 @@ unsigned avdevice_version(void)
 {
     return LIBAVDEVICE_VERSION_INT;
 }
+
+const char * avdevice_configuration(void)
+{
+    return FFMPEG_CONFIGURATION;
+}
+
+const char * avdevice_license(void)
+{
+#define LICENSE_PREFIX "libavdevice license: "
+    return LICENSE_PREFIX FFMPEG_LICENSE + sizeof(LICENSE_PREFIX) - 1;
+}