Implement common logging function

When used as a library, it's desirable to be able to suppress logging,
or pipe logging through a different path.  This commit changes behavior
such that logging is disabled by default, and introduces 2 new methods,
cper_set_log_stdio and cper_set_log_custom.

These allow library integrators to specify their logging mode.  In
practice, this also allows fuzzing to run faster by not printing errors
to the log.

Change-Id: I941476627bc9b8261ba5f6c0b2b2338fdf931dd2
Signed-off-by: Ed Tanous <etanous@nvidia.com>
diff --git a/sections/cper-section-dmar-generic.c b/sections/cper-section-dmar-generic.c
index e745d2b..d75647e 100644
--- a/sections/cper-section-dmar-generic.c
+++ b/sections/cper-section-dmar-generic.c
@@ -9,6 +9,7 @@
 #include <libcper/Cper.h>
 #include <libcper/cper-utils.h>
 #include <libcper/sections/cper-section-dmar-generic.h>
+#include <libcper/log.h>
 
 //Converts a single generic DMAr CPER section into JSON IR.
 json_object *cper_section_dmar_generic_to_ir(const UINT8 *section, UINT32 size)