Move AVEvalExpr declaration at the beginning of the file, where it is

less distracting.

Originally committed as revision 22832 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/eval.h

@@ -28,6 +28,8 @@
 #ifndef AVCODEC_EVAL_H
 #define AVCODEC_EVAL_H
 
+typedef struct ff_expr_s AVEvalExpr;
+
 /**
  * Parses and evaluates an expression.
  * Note, this is significantly slower than ff_parse_eval()
@@ -47,8 +49,6 @@ double ff_eval2(const char *s, const double *const_value, const char * const *co
                double (**func2)(void *, double, double), const char **func2_name,
                void *opaque, const char **error);
 
-typedef struct ff_expr_s AVEvalExpr;
-
 /**
  * Parses a expression.
  * @param s expression as a zero terminated string for example "1+2^3+5*5+sin(2/3)"