Fix varargs use

"man stdarg" says:
  If ap is passed to a function that uses va_arg(ap,type) then the value
  of ap is undefined after the return of that function.

va_start(…) and va_end(…) must be called at each iteration.

By chance, it worked in 32 bits, but it segfaulted in 64 bits.

See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31484

log.c

@@ -389,37 +389,30 @@ static int _log_iterator_next(_log_iterator *it, int level)
   return 0;
 }
 
-static void _log_iterator_vprintf_nl(_log_iterator *it, int level, struct __sourceloc whence, const char *fmt, va_list ap)
-{
-  _log_iterator_rewind(it);
-  while (_log_iterator_next(it, level)) {
-    _log_prefix_whence(it, whence);
-    vxprintf(it->xpf, fmt, ap);
-  }
-}
-
 static void _log_iterator_printf_nl(_log_iterator *it, int level, struct __sourceloc whence, const char *fmt, ...)
 {
   va_list ap;
+  _log_iterator_rewind(it);
+  while (_log_iterator_next(it, level)) {
+    _log_prefix_whence(it, whence);
     va_start(ap, fmt);
-  _log_iterator_vprintf_nl(it, level, whence, fmt, ap);
+    vxprintf(it->xpf, fmt, ap);
     va_end(ap);
   }
-
-static void _logs_vprintf_nl(int level, struct __sourceloc whence, const char *fmt, va_list ap)
-{
-  _log_iterator it;
-  _log_iterator_start(&it);
-  _log_iterator_vprintf_nl(&it, level, whence, fmt, ap);
 }
 
 static void _logs_printf_nl(int level, struct __sourceloc whence, const char *fmt, ...)
 {
   va_list ap;
+  _log_iterator it;
+  _log_iterator_start(&it);
+  while (_log_iterator_next(&it, level)) {
+    _log_prefix_whence(&it, whence);
     va_start(ap, fmt);
-  _logs_vprintf_nl(level, whence, fmt, ap);
+    vxprintf(it.xpf, fmt, ap);
     va_end(ap);
   }
+}
 
 const char *log_file_directory_path()
 {
@@ -681,23 +674,16 @@ void logString(int level, struct __sourceloc whence, const char *str)
 
 void logMessage(int level, struct __sourceloc whence, const char *fmt, ...)
 {
-  if (level != LOG_LEVEL_SILENT) {
   va_list ap;
-    va_start(ap, fmt);
-    vlogMessage(level, whence, fmt, ap);
-    va_end(ap);
-  }
-}
-
-void vlogMessage(int level, struct __sourceloc whence, const char *fmt, va_list ap)
-{
   if (level != LOG_LEVEL_SILENT) {
     _log_iterator it;
     _log_iterator_start(&it);
     _rotate_log_file(&it);
     while (_log_iterator_next(&it, level)) {
       _log_prefix_whence(&it, whence);
+      va_start(ap, fmt);
       vxprintf(it.xpf, fmt, ap);
+      va_end(ap);
     }
   }
 }