jpegdec: move macro to c source

One less semi public symbol without namespace prefix in the headers.

ext/jpeg/gstjpegdec.c

@@ -48,6 +48,9 @@
 #define MIN_HEIGHT 8
 #define MAX_HEIGHT 65535
 
+#define CINFO_GET_JPEGDEC(cinfo_ptr) \
+        (((struct GstJpegDecSourceMgr*)((cinfo_ptr)->src))->dec)
+
 #define JPEG_DEFAULT_IDCT_METHOD	JDCT_FASTEST
 
 enum

ext/jpeg/gstjpegdec.h

@@ -58,9 +58,6 @@ struct GstJpegDecSourceMgr {
   GstJpegDec              *dec;
 };
 
-#define CINFO_GET_JPEGDEC(cinfo_ptr) \
-        (((struct GstJpegDecSourceMgr*)((cinfo_ptr)->src))->dec)
-
 /* Can't use GstBaseTransform, because GstBaseTransform
  * doesn't handle the N buffers in, 1 buffer out case,
  * but only the 1-in 1-out case */