clean memory before use

lib/fimg-file.c

@@ -74,6 +74,7 @@ if (NULL==fp) {
 	return -1;
 	}
 
+memset(&filehead, 0, sizeof(filehead));
 strcpy(filehead.magic, "FIMG");
 filehead.w = fimg->width;	filehead.h = fimg->height;
 filehead.t = fimg->type;