Disable build flatc for tvOS or visionOS (#26380)
### Description
<!-- Describe your changes. -->
To fix build error.
### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
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".
```
