Reduce the visibility of the log style global

Reduce the visibility of the log style global

While $Log_Style is now a global variable, the use of "strict" means that
it is only accessible in lexical scopes where it has been aliased using
the "our" feature.  These are limited, therefore reducing its scope from
a file-scope quasi-global lexical to only the initialization code and the
ftp_syslog function, where it is actually used.