split example_util.h

move ExUtil*File to imageio_util.h
ExUtil*WebP* to webpdec.h

string parsing routines remain

Change-Id: I0560c4a74e86710d83bc4b5b234f1b5ef9a86f9d

imageio/wicdec.c

@@ -33,7 +33,7 @@
 #include <wincodec.h>
 
 #include "webp/encode.h"
-#include "./example_util.h"
+#include "./imageio_util.h"
 #include "./metadata.h"
 
 #define IFS(fn)                                                     \