make gpr_timespec platform agnostic
diff --git a/src/core/support/log_posix.c b/src/core/support/log_posix.c
index 8b050db..8986254 100644
--- a/src/core/support/log_posix.c
+++ b/src/core/support/log_posix.c
@@ -75,16 +75,18 @@
   char *final_slash;
   const char *display_file;
   char time_buffer[64];
+  time_t timer;
   gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
   struct tm tm;
 
+  timer = (time_t)now.tv_sec;
   final_slash = strrchr(args->file, '/');
   if (final_slash == NULL)
     display_file = args->file;
   else
     display_file = final_slash + 1;
 
-  if (!localtime_r(&now.tv_sec, &tm)) {
+  if (!localtime_r(&timer, &tm)) {
     strcpy(time_buffer, "error:localtime");
   } else if (0 ==
              strftime(time_buffer, sizeof(time_buffer), "%m%d %H:%M:%S", &tm)) {