Fix extra field padding check.

Adapt test cases.

lib/zip_extra_field.c

diff --git a/lib/zip_extra_field.c b/lib/zip_extra_field.c
index 258a804..58864cb 100644
--- a/lib/zip_extra_field.c
+++ b/lib/zip_extra_field.c
@@ -253,7 +253,7 @@
 	/* see https://android.googlesource.com/platform/build/+/master/tools/zipalign/ZipAlign.cpp */
 	size_t glen = _zip_buffer_left(buffer);
 	zip_uint8_t *garbage;
-	garbage = _zip_buffer_get(buffer, len);
+	garbage = _zip_buffer_get(buffer, glen);
 	if (glen >= 4 || garbage == NULL || memcmp(garbage, "\0\0\0", glen) != 0) {
 	    zip_error_set(error, ZIP_ER_INCONS, 0);
 	    _zip_buffer_free(buffer);