MINOR: trace: make trace sources read_mostly
The trace sources are checked at plenty of places in the code and their
contents only change when trace status changes, let's mark them read_mostly.
diff --git a/src/mux_fcgi.c b/src/mux_fcgi.c
index ddb2a60..f938a57 100644
--- a/src/mux_fcgi.c
+++ b/src/mux_fcgi.c
@@ -335,7 +335,7 @@
{ /* end */ }
};
-static struct trace_source trace_fcgi = {
+static struct trace_source trace_fcgi __read_mostly = {
.name = IST("fcgi"),
.desc = "FastCGI multiplexer",
.arg_def = TRC_ARG1_CONN, // TRACE()'s first argument is always a connection