Use extern C guards in all headers

The project uses a mix of C and C++ requiring
extern "C" guards from C++ code both within the
project & from C++ apps that use libcper. That
won't be required with this change.

Change-Id: I835dd05166732ca213c72eae2904815a8769599b
Signed-off-by: Karthik Rajagopalan <krajagopalan@nvidia.com>
diff --git a/sections/cper-section-ipf.h b/sections/cper-section-ipf.h
index cf346ef..9e265db 100644
--- a/sections/cper-section-ipf.h
+++ b/sections/cper-section-ipf.h
@@ -1,6 +1,10 @@
 #ifndef CPER_SECTION_IPF_H
 #define CPER_SECTION_IPF_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #include <json.h>
 #include "../edk/Cper.h"
 
@@ -69,4 +73,8 @@
 
 json_object *cper_section_ipf_to_ir(void *section);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif