log: Make sure the buffer for date is big enough

src/log.c:71:32: error: '%06ld' directive output may be truncated
writing between 6 and 20 bytes into a region of size between 0 and 63
[-Werror=format-truncation=]
         snprintf(buf, len, "%s.%06ld", tbuf, (long)tv.tv_usec);

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>
(cherry picked from commit 6766b0a860)

src/log.c

@@ -81,7 +81,7 @@ static void ssh_log_stderr(int verbosity,
                            const char *function,
                            const char *buffer)
 {
-    char date[64] = {0};
+    char date[128] = {0};
     int rc;
 
     rc = current_timestring(1, date, sizeof(date));