share debug.[ch] across all executables

This avoids us having to re-define log_info/log_info_cat for each
program.

Change-Id: I22f4f8a51b91ee09c5be26b1ed1bfca41730c577
diff --git a/src/debug.h b/src/debug.h
index 187d895..02551eb 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -3,3 +3,5 @@
 enum {
 	DMAIN,
 };
+
+extern const struct log_info log_info;