Handle improperly build image files gracefully

Images build improperly (by simply concatenating separate images) were accepted,
but anything after the first end-of-file record *silently* ignored. Now emit warning
for intel and motorola images upon non-whitespace after first end-of-file record but
continue reading anyway.
ST ships some images broken that way in their CubeMX packages ...

Change-Id: I0c5d08fa90070fed11fb805c5f0dc39817048176
Signed-off-by: Andreas Bolsch <hyphen0break@gmail.com>
Reviewed-on: http://openocd.zylin.com/4281
Tested-by: jenkins
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

src/helper/fileio.c

@@ -153,6 +153,11 @@ int fileio_close(struct fileio *fileio)
 	return retval;
 }
 
+int fileio_feof(struct fileio *fileio)
+{
+	return feof(fileio->file);
+}
+
 int fileio_seek(struct fileio *fileio, size_t position)
 {
 	int retval;

src/helper/fileio.h

@@ -46,6 +46,7 @@ struct fileio;
 int fileio_open(struct fileio **fileio, const char *url,
 		enum fileio_access access_type, enum fileio_type type);
 int fileio_close(struct fileio *fileio);
+int fileio_feof(struct fileio *fileio);
 
 int fileio_seek(struct fileio *fileio, size_t position);
 int fileio_fgets(struct fileio *fileio, size_t size, void *buffer);