Turn DPRINTF into a wrapper to a generic logging function

DPRINTF() made a generic logging function taking a va_list called
vlogger() and reimplemented as a wrapper on top of vlogger().

src/logger.c

@@ -70,7 +70,7 @@ set_logdomains(char *domains)
 }
 
 void
-DPRINTF(int severity, int domain, char *fmt, ...)
+vlogger(int severity, int domain, char *fmt, va_list args)
 {
   va_list ap;
   char stamp[32];
@@ -97,7 +97,7 @@ DPRINTF(int severity, int domain, char *fmt, ...)
 
       fprintf(logfile, "[%s] %6s: ", stamp, labels[domain]);
 
-      va_start(ap, fmt);
+      va_copy(ap, args);
       vfprintf(logfile, fmt, ap);
       va_end(ap);
     }
@@ -106,7 +106,7 @@ DPRINTF(int severity, int domain, char *fmt, ...)
     {
       fprintf(stderr, "%6s: ", labels[domain]);
 
-      va_start(ap, fmt);
+      va_copy(ap, args);
       vfprintf(stderr, fmt, ap);
       va_end(ap);
     }
@@ -114,6 +114,16 @@ DPRINTF(int severity, int domain, char *fmt, ...)
   pthread_mutex_unlock(&logger_lck);
 }
 
+void
+DPRINTF(int severity, int domain, char *fmt, ...)
+{
+  va_list ap;
+
+  va_start(ap, fmt);
+  vlogger(severity, domain, fmt, ap);
+  va_end(ap);
+}
+
 void
 logger_libevent(int severity, const char *msg)
 {

src/logger.h

@@ -2,6 +2,8 @@
 #ifndef __LOGGER_H__
 #define __LOGGER_H__
 
+#include <stdarg.h>
+
 /* Log domains */
 #define L_CONF    0
 #define L_DAAP    1
@@ -30,6 +32,9 @@
 #define E_SPAM    5
 
 
+void
+vlogger(int severity, int domain, char *fmt, va_list args);
+
 void
 DPRINTF(int severity, int domain, char *fmt, ...);