libebml: fix compilation with GCC11

Signed-off-by: Rosen Penev <rosenp@gmail.com>

libs/libebml/patches/010-gcc11.patch

@@ -0,0 +1,20 @@
+--- 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"
+ 
+--- a/src/EbmlUnicodeString.cpp
++++ b/src/EbmlUnicodeString.cpp
+@@ -36,6 +36,7 @@
+ */
+ 
+ #include <cassert>
++#include <limits>
+ 
+ #include "ebml/EbmlUnicodeString.h"
+