Disable build flatc for tvOS or visionOS

[hans00]

Description

To fix build error.

Motivation and Context

Currently will build fail.

CMake Error at /Users/runner/work/onnxruntime-custom/onnxruntime-custom/tvOS/RelWithDebInfo/_deps/flatbuffers-src/CMakeLists.txt:636 (install):
-- CMAKE_CXX_FLAGS: -DNDEBUG -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fstack-protector-strong -O3 -pipe -g -ffunction-sections -fdata-sections -fvisibility=hidden -fvisibility-inlines-hidden -DCPUINFO_SUPPORTED
  install TARGETS given no BUNDLE DESTINATION for MACOSX_BUNDLE executable
  target "flatc".