layout: Add capacity field

Use it to keep track of the size of the `entries` array. An interim
solution until we have dynamic allocation.

Change-Id: Ib5f431bc0a72a79a53fa1376c3417942b19dd3a0
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/33516
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Reviewed-by: Peter Marheine <pmarheine@chromium.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

layout.h

@@ -46,6 +46,8 @@ struct romentry {
 struct flashrom_layout {
 	/* entries store the entries specified in a layout file and associated run-time data */
 	struct romentry *entries;
+	/* the maximum number of entries */
+	size_t capacity;
 	/* the number of successfully parsed entries */
 	size_t num_entries;
 };