userfaultfd is available as a syscall on Android and is used by some system components, but it is not accessible to regular application processes. Since Android 8.0, seccomp filters applied to app processes block this syscall, resulting in a fatal SIGSYS instead of a recoverable error. Wine runs inside the Android app sandbox, so attempting to use userfaultfd leads to an immediate crash during startup. This change disables userfaultfd usage on Android to avoid invoking a forbidden syscall. I am aware that platform-specific macros are generally discouraged. I would appreciate guidance on a more appropriate way to handle this condition if there is a preferred abstraction or runtime check. With this change, Wine successfully starts on the `Google Play Intel x86 Atom System Image` (API 26) in the Android Emulator, although there are still rendering issues (inverted colors, AVD does not work well with BGRA buffers). <details> <summary>Screenshot</summary> {width=883 height=600} </details> -- https://gitlab.winehq.org/wine/wine/-/merge_requests/10516