contribs: ebml: Fix build with GCC11

Already applied upstream

contrib/src/ebml/missing-limits-include.patch

+From f0bfd53647961e799a43d918c46cf3b6bff89806 Mon Sep 17 00:00:00 2001
+From: Moritz Bunkus <mo@bunkus.online>
+Date: Sat, 27 Feb 2021 20:36:52 +0100
+Subject: [PATCH] include appropriate header files for std::numeric_limits
+
+Fixes #80.
+---
+ ChangeLog                 | 4 ++++
+ src/EbmlString.cpp        | 1 +
+ src/EbmlUnicodeString.cpp | 1 +
+ 3 files changed, 6 insertions(+)
+
+diff --git a/src/EbmlString.cpp b/src/EbmlString.cpp
+index 27e55fd..4c05fcf 100644
+--- a/src/EbmlString.cpp
++++ b/src/EbmlString.cpp
+@@ -34,6 +34,7 @@
+   \author Steve Lhomme     <robux4 @ users.sf.net>
+ */
+ #include <cassert>
++#include <limits>
+ 
+ #include "ebml/EbmlString.h"
+ 
+diff --git a/src/EbmlUnicodeString.cpp b/src/EbmlUnicodeString.cpp
+index 496a16a..99fc073 100644
+--- a/src/EbmlUnicodeString.cpp
++++ b/src/EbmlUnicodeString.cpp
+@@ -36,6 +36,7 @@
+ */
+ 
+ #include <cassert>
++#include <limits>
+ 
+ #include "ebml/EbmlUnicodeString.h"
+ 

contrib/src/ebml/rules.mak

@@ -14,6 +14,7 @@ $(TARBALLS)/libebml-$(EBML_VERSION).tar.xz:
 
 ebml: libebml-$(EBML_VERSION).tar.xz .sum-ebml
 	$(UNPACK)
+	$(APPLY) $(SRC)/ebml/missing-limits-include.patch
 	$(MOVE)
 
 .ebml: ebml toolchain.cmake