Fix regexp import in ossec-batch-manager.pl

[seren]

Hi, this fixes what appears to be a syntax error in the user-contributed file ossec-batch-manager.pl. Currently it produces the error:

Global symbol "%RE" requires explicit package name (did you forget to declare "my %RE"?) at ./ossec-batch-manager.pl line 105.
Global symbol "%RE" requires explicit package name (did you forget to declare "my %RE"?) at ./ossec-batch-manager.pl line 107.
BEGIN not safe after errors--compilation aborted at ./ossec-batch-manager.pl line 139.

Fixes #1914

[atomicturtle]

Excellent, thanks for the commit!