perf trace/scripting: Ignore shadowed variable warning for perf-trace-perl.c

The debugging versions of the ENTER and LEAVE internal perl
macros, used when embedding perl, define a local block with a
my_perl perl variable that shadows a global variable of the same
name, which is also the name expected by the embedding API for
the embedded interpreter.

Since we don't have control over the code generated in this case
(it's an externality) and can't get rid of the warning, ignore it.

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: fweisbec@gmail.com
Cc: rostedt@goodmis.org
Cc: anton@samba.org
Cc: hch@infradead.org
LKML-Reference: <1259565529-6407-3-git-send-email-tzanussi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>