Refactor, _d() et al to use logit() instead of err.h

This patch is the first in a series of changes to clean up the internal
logging APIs of Finit:

  1. Convert log macros to use logit() for everything (this patch)
  2. Set correct syslog() log level based on debug flag
  3. Do closelog()/openlog() when toggling debug flag to control LOG_PERROR

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

src/helpers.c

@@ -39,8 +39,6 @@
 #include "private.h"
 #include "utmp-api.h"
 
-int _slup = 0;			/* INTERNAL: Is syslog up yet? */
-
 char *strip_line(char *line)
 {
 	char *ptr;