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/generator/cper-generate-cli.c b/generator/cper-generate-cli.c
index b0bf14d..c9882c2 100644
--- a/generator/cper-generate-cli.c
+++ b/generator/cper-generate-cli.c
@@ -7,9 +7,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include "Cper.h"
-#include "cper-generate.h"
-#include "sections/gen-section.h"
+#include <libcper/Cper.h>
+#include <libcper/generator/cper-generate.h>
+#include <libcper/generator/sections/gen-section.h>
 
 void print_help();