pngcp.c: correct total time output

Signed-off-by: John Bowler <jbowler@acm.org>
diff --git a/contrib/tools/pngcp.c b/contrib/tools/pngcp.c
index 829a449..924d6e9 100644
--- a/contrib/tools/pngcp.c
+++ b/contrib/tools/pngcp.c
@@ -2420,12 +2420,12 @@
             int output = 0;
 
             if ((d.value[OPTIND(&d,time)] & PNGCP_TIME_READ) != 0)
-               print_time("read", d.read_time), output = 1;
+               print_time("read", d.read_time_total), output = 1;
 
             if ((d.value[OPTIND(&d,time)] & PNGCP_TIME_WRITE) != 0)
             {
                if (output) putchar(' ');
-               print_time("write", d.write_time);
+               print_time("write", d.write_time_total);
                output = 1;
             }