[PATCH] perf: fix extern struct definitions

[Stephane Eranian <eranian@google.com>]

Both python_scripting_ops and perl_scripting_ops have two global definitions.
One in trace-event-scripting.c and one in their respective scripting-engine
modules.

The issue is that depending on the linker order one definition or the other
is chosen. One is uninitialized (bss), while the other is initialized. If
the uninitialized version is chosen, then perf does not function properly.

This patch fixes this by adding the extern prefix to the definitions in
trace-event-scripting.c. 

Signed-off-by: Stephane Eranian <eranian@google.com>

diff --git a/tools/perf/util/trace-event-scripting.c b/tools/perf/util/trace-event-scripting.c
index 7ea983a..f7af2fc 100644
--- a/tools/perf/util/trace-event-scripting.c
+++ b/tools/perf/util/trace-event-scripting.c
@@ -97,7 +97,7 @@ void setup_python_scripting(void)
 	register_python_scripting(&python_scripting_unsupported_ops);
 }
 #else
-struct scripting_ops python_scripting_ops;
+extern struct scripting_ops python_scripting_ops;
 
 void setup_python_scripting(void)
 {
@@ -158,7 +158,7 @@ void setup_perl_scripting(void)
 	register_perl_scripting(&perl_scripting_unsupported_ops);
 }
 #else
-struct scripting_ops perl_scripting_ops;
+extern struct scripting_ops perl_scripting_ops;
 
 void setup_perl_scripting(void)
 {