tracing/core: Turn ftrace_cpu_disabled into a global var

In order to prepare the moving of the function graph tracer insertion
helpers from trace.c to trace_functions_graph.c, we need to export the
ftrace_cpu_disabled variable.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

@@ -89,7 +89,7 @@ static int dummy_set_flag(u32 old_flags, u32 bit, int set)
  */
 static int tracing_disabled = 1;
 
-static DEFINE_PER_CPU(local_t, ftrace_cpu_disabled);
+DEFINE_PER_CPU(local_t, ftrace_cpu_disabled);
 
 static inline void ftrace_disable_cpu(void)
 {

kernel/trace/trace.h

@@ -519,6 +519,7 @@ extern int DYN_FTRACE_TEST_NAME(void);
 
 extern int ring_buffer_expanded;
 extern bool tracing_selftest_disabled;
+DECLARE_PER_CPU(local_t, ftrace_cpu_disabled);
 
 #ifdef CONFIG_FTRACE_STARTUP_TEST
 extern int trace_selftest_startup_function(struct tracer *trace,