zdump/dfo_s390: Support s390 DFO for vr-kernel dumps

Since memory chunks can overlap for vr-kernel dumps stored in elf
format (ngdump, zfcpdump), we need to consider this when converting to
s390 dump output format. For that sort DFI memory chunks by start
address and adjust dfo_s390 logic for identifying memory gaps.
Otherwise we might end up with bogus DFO memory chunks being created.

Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdump/dfi.c

@@ -809,6 +809,8 @@ int dfi_init(void)
 		l.dfi = dfi;
 		g.fh = dfi_dump_open(g.opts.device);
 		rc = dfi->init();
+		if (rc == 0)
+			dfi_mem_chunk_sort();
 		if (rc == 0 && dfi_feat_seek()) {
 			kdump_init();
 			dfi_vmcoreinfo_init();