swscale: Add test for isSemiPlanarYUV to pixdesc_query

Lauri had asked me what the semi planar formats were and that reminded
me that we could add it to pixdesc_query so we know exactly what the
list is.

libswscale/tests/pixdesc_query.c

@@ -32,6 +32,7 @@ static const struct {
     {"isBE",        isBE},
     {"isYUV",       isYUV},
     {"isPlanarYUV", isPlanarYUV},
+    {"isSemiPlanarYUV", isSemiPlanarYUV},
     {"isRGB",       isRGB},
     {"Gray",        isGray},
     {"RGBinInt",    isRGBinInt},

tests/ref/fate/sws-pixdesc-query

@@ -347,6 +347,19 @@ isPlanarYUV:
   yuvj440p
   yuvj444p
 
+isSemiPlanarYUV:
+  nv12
+  nv16
+  nv20be
+  nv20le
+  nv21
+  nv24
+  nv42
+  p010be
+  p010le
+  p016be
+  p016le
+
 isRGB:
   0bgr
   0rgb