Fix trace dependency mess

src/core/lib/debug/trace.c

@@ -35,11 +35,12 @@
 
 #include <string.h>
 
-#include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include "src/core/lib/support/env.h"
 
+int grpc_tracer_set_enabled(const char *name, int enabled);
+
 typedef struct tracer {
   const char *name;
   grpc_tracer_flag *flag;