feat(util): Add log function for logging in exception handlers

We want this to always be visible, so the log level must be
the highest possible. Unfortunately, that's quite the hack
around the existing API and how fatal behaves.

The log API stopped scaling already a while ago and needs
considerable refactoring to consider the various use-cases
that emerged since it was first created on alpha versions
of bemanitools.

src/main/util/log.c

@@ -64,6 +64,15 @@ static void log_builtin_format(
     }
 }
 
+void log_exception_handler(const char *fmt, ...)
+{
+    va_list ap;
+
+    va_start(ap, fmt);
+    log_builtin_format(LOG_LEVEL_FATAL, LOG_MODULE, fmt, ap);
+    va_end(ap);
+}
+
 void log_assert_body(const char *file, int line, const char *function)
 {
     log_impl_fatal("assert", "%s:%d: function `%s'", file, line, function);