Fix an ABI compatibility issue with ast_log_safe for modules.

Binary modules are sometimes built against the latest release of
Asterisk in each branch, and need to be compatible with all
releases of that branch.  This change ensures that utils.h only
uses ast_log_safe from the core.  For modules and utilities ast_log
is used instead.

Review: https://reviewboard.asterisk.org/r/4548/
........

Merged revisions 433772 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/13@433773 65c4cc65-6c06-0410-ace0-fbb531ad65f3