Patch upb to fix build error with gcc 10 (third_party)

Closes bazelbuild#12088

third_party/grpc/BUILD

@@ -18,7 +18,7 @@ load("//tools/distributions:distribution_rules.bzl", "distrib_java_import", "dis
 
 licenses(["notice"])  # Apache v2
 
-exports_files(["grpc_1.26.0.patch"])
+exports_files(["grpc_1.26.0.patch", "upb_gcc10_fix.patch"])
 
 package(default_visibility = ["//visibility:public"])
 

third_party/grpc/upb_gcc10_fix.patch

@@ -0,0 +1,51 @@
+commit 9bd23dab4240b015321a53c45b3c9e4847fbf020
+Author: Joshua Haberman <jhaberman@gmail.com>
+Date:   Tue Apr 7 15:22:11 2020 -0700
+
+    Changed upb status to suit GCC10's warning about strncpy(). (#268)
+
+    Added tests for all cases. Also removed ellipses from truncated
+    messages, they were more trouble than they are worth.
+
+diff --git a/upb/upb.c b/upb/upb.c
+index cb2cdfd..258192d 100644
+--- a/upb/upb.c
++++ b/upb/upb.c
+@@ -11,17 +11,6 @@
+
+ #include "upb/port_def.inc"
+
+-/* Guarantee null-termination and provide ellipsis truncation.
+- * It may be tempting to "optimize" this by initializing these final
+- * four bytes up-front and then being careful never to overwrite them,
+- * this is safer and simpler. */
+-static void nullz(upb_status *status) {
+-  const char *ellipsis = "...";
+-  size_t len = strlen(ellipsis);
+-  UPB_ASSERT(sizeof(status->msg) > len);
+-  memcpy(status->msg + sizeof(status->msg) - len, ellipsis, len);
+-}
+-
+ /* upb_status *****************************************************************/
+
+ void upb_status_clear(upb_status *status) {
+@@ -37,8 +26,8 @@ const char *upb_status_errmsg(const upb_status *status) { return status->msg; }
+ void upb_status_seterrmsg(upb_status *status, const char *msg) {
+   if (!status) return;
+   status->ok = false;
+-  strncpy(status->msg, msg, sizeof(status->msg));
+-  nullz(status);
++  strncpy(status->msg, msg, UPB_STATUS_MAX_MESSAGE - 1);
++  status->msg[UPB_STATUS_MAX_MESSAGE - 1] = '\0';
+ }
+
+ void upb_status_seterrf(upb_status *status, const char *fmt, ...) {
+@@ -52,7 +41,7 @@ void upb_status_vseterrf(upb_status *status, const char *fmt, va_list args) {
+   if (!status) return;
+   status->ok = false;
+   _upb_vsnprintf(status->msg, sizeof(status->msg), fmt, args);
+-  nullz(status);
++  status->msg[UPB_STATUS_MAX_MESSAGE - 1] = '\0';
+ }
+
+ /* upb_alloc ******************************************************************/