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/generator/cper-generate-cli.c b/generator/cper-generate-cli.c
index 8c570ab..036aaeb 100644
--- a/generator/cper-generate-cli.c
+++ b/generator/cper-generate-cli.c
@@ -7,6 +7,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <libcper/log.h>
 #include <libcper/Cper.h>
 #include <libcper/generator/cper-generate.h>
 #include <libcper/generator/sections/gen-section.h>
@@ -15,6 +16,7 @@
 
 int main(int argc, char *argv[])
 {
+	cper_set_log_stdio();
 	//If help requested, print help.
 	if (argc == 2 && strcmp(argv[1], "--help") == 0) {
 		print_help();
diff --git a/generator/cper-generate.c b/generator/cper-generate.c
index 8675a78..b1b105b 100644
--- a/generator/cper-generate.c
+++ b/generator/cper-generate.c
@@ -7,6 +7,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <libcper/log.h>
 #include <libcper/Cper.h>
 #include <libcper/generator/gen-utils.h>
 #include <libcper/generator/sections/gen-section.h>