avutil/opt: Fix types used to access AV_OPT_TYPE_PIXEL_FMT

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit a0640e63)
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavutil/opt.c

@@ -75,7 +75,7 @@ static int read_number(const AVOption *o, void *dst, double *num, int *den, int6
 {
     switch (o->type) {
     case AV_OPT_TYPE_FLAGS:     *intnum = *(unsigned int*)dst;return 0;
-    case AV_OPT_TYPE_PIXEL_FMT:
+    case AV_OPT_TYPE_PIXEL_FMT: *intnum = *(enum AVPixelFormat *)dst;return 0;
     case AV_OPT_TYPE_SAMPLE_FMT:
     case AV_OPT_TYPE_INT:       *intnum = *(int         *)dst;return 0;
     case AV_OPT_TYPE_CHANNEL_LAYOUT:
@@ -110,8 +110,8 @@ static int write_number(void *obj, const AVOption *o, void *dst, double num, int
     }
 
     switch (o->type) {
+    case AV_OPT_TYPE_PIXEL_FMT: *(enum AVPixelFormat *)dst = llrint(num/den) * intnum; break;
     case AV_OPT_TYPE_FLAGS:
-    case AV_OPT_TYPE_PIXEL_FMT:
     case AV_OPT_TYPE_SAMPLE_FMT:
     case AV_OPT_TYPE_INT:   *(int       *)dst= llrint(num/den)*intnum; break;
     case AV_OPT_TYPE_DURATION: