Rename "AVClass class" as "AVClass component_class" for external codecs.

The aix header math.h defines "extern int class()" for C.
This fixes compilation on aix with external libraries enabled.

Signed-off-by: Carl Eugen Hoyos <cehoyos@ag.or.at>

libavcodec/libopenjpegenc.c

@@ -542,7 +542,7 @@ static const AVOption options[] = {
     { NULL },
 };
 
-static const AVClass class = {
+static const AVClass openjpeg_class = {
     .class_name = "libopenjpeg",
     .item_name  = av_default_item_name,
     .option     = options,
@@ -577,5 +577,5 @@ AVCodec ff_libopenjpeg_encoder = {
         AV_PIX_FMT_NONE
     },
     .long_name      = NULL_IF_CONFIG_SMALL("OpenJPEG JPEG 2000"),
-    .priv_class     = &class,
+    .priv_class     = &openjpeg_class,
 };