perf trace/scripting: Fix Perl common_* access functions

The common_* functions (e.g. common_pc(), etc) are exported as
common_* but named get_common_*, resulting in unresolved
subroutine errors when executing scripts.

Make the internal and external names match.

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: <1259565529-6407-4-git-send-email-tzanussi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>