pin flatbuffers 23.5.26

https://github.com/microsoft/onnxruntime/blob/45737400a2f3015c11f005ed7603611eaed306a6/onnxruntime/core/providers/dml/DmlExecutionProvider/src/External/DirectMLHelpers/DmlGraphDesc_generated.h#L11

vcpkg-overlay/ports/flatbuffers/fix-uwp-build.patch

@@ -0,0 +1,20 @@
+diff --git a/src/util.cpp b/src/util.cpp
+index aabc23a..06e9ebe 100644
+--- a/src/util.cpp
++++ b/src/util.cpp
+@@ -434,9 +434,15 @@ bool ReadEnvironmentVariable(const char *var_name, std::string *_value) {
+ #ifdef _MSC_VER
+   __pragma(warning(disable : 4996));  // _CRT_SECURE_NO_WARNINGS
+ #endif
++#if _WIN32_WINNT < 0x0A00
+   auto env_str = std::getenv(var_name);
+   if (!env_str) return false;
+   if (_value) *_value = std::string(env_str);
++#else
++  //There is no support for environment variables in UWP
++  var_name; // Do nothing
++  *_value = std::string("");
++#endif
+   return true;
+ }
+

vcpkg-overlay/ports/flatbuffers/portfile.cmake

@@ -0,0 +1,47 @@
+vcpkg_check_linkage(ONLY_STATIC_LIBRARY)
+
+vcpkg_from_github(
+    OUT_SOURCE_PATH SOURCE_PATH
+    REPO google/flatbuffers
+    REF "v${VERSION}"
+    SHA512 cd0a5efad8016e1217d01a181d6b02e546f5693c6412361bfeaee820d5dfe5e2a424cee1963270e851c1a4f936ae8a0032a51c5bb16ee19313e0ecc77dc4ba31
+    HEAD_REF master
+    PATCHES
+        fix-uwp-build.patch
+)
+
+set(options "")
+if(VCPKG_CROSSCOMPILING)
+    list(APPEND options -DFLATBUFFERS_BUILD_FLATC=OFF -DFLATBUFFERS_BUILD_FLATHASH=OFF)
+    if(VCPKG_TARGET_IS_OSX OR VCPKG_TARGET_IS_IOS)
+        # The option may cause "#error Unsupported architecture"
+        list(APPEND options -DFLATBUFFERS_OSX_BUILD_UNIVERSAL=OFF)
+    endif()
+endif()
+
+vcpkg_cmake_configure(
+    SOURCE_PATH "${SOURCE_PATH}"
+    OPTIONS
+        -DFLATBUFFERS_BUILD_TESTS=OFF
+        -DFLATBUFFERS_BUILD_GRPCTEST=OFF
+        ${options}
+)
+
+vcpkg_cmake_install()
+vcpkg_cmake_config_fixup(CONFIG_PATH lib/cmake/flatbuffers)
+vcpkg_fixup_pkgconfig()
+
+file(GLOB flatc_path ${CURRENT_PACKAGES_DIR}/bin/flatc*)
+if(flatc_path)
+    vcpkg_copy_tools(TOOL_NAMES flatc AUTO_CLEAN)
+else()
+    file(APPEND "${CURRENT_PACKAGES_DIR}/share/flatbuffers/flatbuffers-config.cmake"
+"\ninclude(\"\${CMAKE_CURRENT_LIST_DIR}/../../../${HOST_TRIPLET}/share/flatbuffers/FlatcTargets.cmake\")\n")
+endif()
+
+file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/debug/include")
+file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/debug/share")
+file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/bin" "${CURRENT_PACKAGES_DIR}/debug/bin")
+
+# Handle copyright
+vcpkg_install_copyright(FILE_LIST "${SOURCE_PATH}/LICENSE")

vcpkg-overlay/ports/flatbuffers/vcpkg.json

@@ -0,0 +1,21 @@
+{
+  "name": "flatbuffers",
+  "version": "23.5.26",
+  "description": "FlatBuffers is a cross platform serialization library architected for maximum memory efficiency. It allows you to directly access serialized data without parsing/unpacking it first, while still having great forwards/backwards compatibility.",
+  "homepage": "https://google.github.io/flatbuffers/",
+  "license": "Apache-2.0",
+  "dependencies": [
+    {
+      "name": "flatbuffers",
+      "host": true
+    },
+    {
+      "name": "vcpkg-cmake",
+      "host": true
+    },
+    {
+      "name": "vcpkg-cmake-config",
+      "host": true
+    }
+  ]
+}