Add stacktrace generation to maxbase

The stacktrace generation is now a part of the maxbase library. The code
is the same code that was previously defined in gateway.cc as a part of
MaxScale.

maxutils/maxbase/include/maxbase/stacktrace.hh

@@ -0,0 +1,32 @@
+#pragma once
+/*
+ * Copyright (c) 2018 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2020-01-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#include <maxbase/ccdefs.hh>
+#include <unistd.h>
+#include <cstring>
+
+namespace maxbase
+{
+
+static inline void default_stacktrace_handler(const char* symbol, const char* command)
+{
+    write(STDOUT_FILENO, symbol, strlen(symbol));
+    write(STDOUT_FILENO, ": ", 2);
+    write(STDOUT_FILENO, command, strlen(command));
+    write(STDOUT_FILENO, "\n", 1);
+}
+
+void dump_stacktrace(void (*handler)(const char* symbol, const char* command) = default_stacktrace_handler);
+
+}