db: add generic warn/error function.

This avoids the mess where we override db_fatal for teqsts, and keeps it
generic.

Also allows us to get rid of one #if DEVELOPER, and an ugly global for
bookkeeper.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

db/common.h

@@ -6,6 +6,7 @@
 #include <ccan/strset/strset.h>
 #include <common/autodata.h>
 #include <common/utils.h>
+#include <stdarg.h>
 
 /**
  * Macro to annotate a named SQL query.
@@ -35,6 +36,10 @@ struct db {
 	/* DB-specific context */
 	void *conn;
 
+	/* function to log warnings, or fail (if fatal == true). vprintf-style */
+	void (*errorfn)(void *arg, bool fatal, const char *fmt, va_list ap);
+	void *errorfn_arg;
+
 	/* The configuration for the current database driver */
 	const struct db_config *config;
 
@@ -183,9 +188,6 @@ struct db_config {
 			       const char **colnames, size_t num_cols);
 };
 
-void db_fatal(const char *fmt, ...)
-	PRINTF_FMT(1, 2);
-
 /* Provide a way for DB backends to register themselves */
 AUTODATA_TYPE(db_backends, struct db_config);