Log variables moved to log_manager.h

The log manager variables lm_enabled_log_files_bitmask, log_ses_count
and tls_log_info that earlier were declared separately in every
c-file are now declared in the log_manager.h header.

server/core/dbusers.c

@@ -105,10 +105,6 @@
 #define ERROR_NO_SHOW_DATABASES "%s: Unable to load database grant information, \
     MaxScale authentication will proceed without including database permissions. \
     To correct this GRANT SHOW DATABASES ON *.* privilege to the user %s."
-/** Defined in log_manager.cc */
-extern int            lm_enabled_logfiles_bitmask;
-extern size_t         log_ses_count[];
-extern __thread log_info_t tls_log_info;
 
 static int getUsers(SERVICE *service, USERS *users);
 static int uh_cmpfun( void* v1, void* v2);