net/rocker: use GDateTime for formatting timestamp in debug messages

The GDateTime APIs provided by GLib avoid portability pitfalls, such
as some platforms where 'struct timeval.tv_sec' field is still 'long'
instead of 'time_t'. When combined with automatic cleanup, GDateTime
often results in simpler code too.

Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

hw/net/rocker/rocker.h

@@ -25,14 +25,9 @@
 #if defined(DEBUG_ROCKER)
 #  define DPRINTF(fmt, ...) \
     do {                                                           \
-        struct timeval tv;                                         \
-        char timestr[64];                                          \
-        time_t now;                                                \
-        gettimeofday(&tv, NULL);                                   \
-        now = tv.tv_sec;                                           \
-        strftime(timestr, sizeof(timestr), "%T", localtime(&now)); \
-        fprintf(stderr, "%s.%06ld ", timestr, tv.tv_usec);         \
-        fprintf(stderr, "ROCKER: " fmt, ## __VA_ARGS__);           \
+        g_autoptr(GDateTime) now = g_date_time_new_now_local();    \
+        g_autofree char *nowstr = g_date_time_format(now, "%T.%f");\
+        fprintf(stderr, "%s ROCKER: " fmt, nowstr, ## __VA_ARGS__);\
     } while (0)
 #else
 static inline GCC_FMT_ATTR(1, 2) int DPRINTF(const char *fmt, ...)