Change include style to use system includes

The libcper header files in `libcper` are installed to
`usr/include/libcper`. Use that system includes in `libcper` source
instead of using the project includes.

Change-Id: I596edc2c754dae4829844f535a1e34caa246fb43
Signed-off-by: Thu Nguyen <thu@os.amperecomputing.com>
diff --git a/cper-parse.i b/cper-parse.i
index e783e7d..45c8d3a 100644
--- a/cper-parse.i
+++ b/cper-parse.i
@@ -1,6 +1,6 @@
 % module cperparse %
 	{
-#include "cper-parse.h"
+#include <libcper/cper-parse.h>
 #include <json.h>
 #include <stdio.h>
 		%