Fix LTO linking issues on CachyOS with GCC 15.x
- Add LTO support to all core library targets (input_common, frontend_common,
network, shader_recompiler, web_service) that were missing LTO configuration
- Create citron_configure_lto() helper function for consistent LTO handling
- Implement CachyOS-specific detection via /etc/os-release and kernel version
- Apply conservative LTO flags (-flto=auto -ffat-lto-objects) only for
CachyOS + GCC 15+ to resolve linking errors with newer toolchains
- Other distributions continue using aggressive LTO settings for maximum performance
- Disable LTO on executable targets to prevent main function optimization issues
This resolves "undefined symbol" errors when building with -DCITRON_ENABLE_LTO=ON
on CachyOS while maintaining optimal LTO performance on other distributions.
Fixes linking errors including:
- Core::Frontend::EmuWindow symbols
- Core::System methods
- Settings::values
- Common logging functions
Tested on CachyOS with GCC 15.1.1 + LLD 20.1.8
Signed-off-by: Boss.sfc <boss.sfc@citron-emu.org>
