Print stack trace on assert() failure or when calling fatal_error()

Note: this uses the __sanitizer_print_stack_trace() function from the
AddressSanitizer runtime, so it only works when AddressSanitizer is
in use.

log.c

@@ -1,15 +1,15 @@
 #include "log.h"
 
-#include <stdlib.h>
-#include <stdio.h>
-#include <stdarg.h>
-#include <string.h>
-#include <stdbool.h>
 #include <errno.h>
-#include <assert.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syslog.h>
 #include <unistd.h>
 
-#include <syslog.h>
+#include "debug.h"
 
 static bool colorize = false;
 static bool do_syslog = true;