GeezerVison

#140249 inadvertently disabled checking for statx on Android because MACHDEP is "android" on Android. You can verify this by looking at the logs from the Android runner from #140249. This is a cross-compile. In the "Configure build Python" logs, MACHDEP is linux and configure checks for statx; in the "Configure host Python" logs, MACHDEP is android and configure doesn't check for statx (would be just after checking for writev).

Base the check for statx on ac_sys_system instead, which is Linux-android on Android, Linux on other Linux distributions, and AIX on AIX (which has an incompatible function named statx that prompted #140249).

Before merging:

• Please look at the Android build log to make sure both the build and host Python configure check for statx. (The host Python check will result in no because the Android CI uses Android API level 24 and statx was introduced in Android API level 30.) Verified, the host Python configure checks for statx.
  • People are building for API levels higher than 30, given issue #123014, so this PR is not theoretical.
• If the Android buildbots still exist and use API level 30 or higher (#123014 indicates they "will" use 34), please run the Android buildbots to make sure the tests pass. (I can't do this myself.)

cc @ayappanec as author of #140249
cc @vstinner as reviewer of statx-related PRs
cc @mhsmith as Android buildbot operator and Android maintainer

(There's a "$MACHDEP" != linux check just below the code this PR changes, which does not exclude Android as may have been intended. Android introduced lchmod in API level 36. lchmod delegates to fchmodat with AT_SYMLINK_NOFOLLOW, and fchmodat has code that should work on non-symlinks and give the correct errno for symlinks, so I think the behavior is acceptable, but we aren't testing it. That can be a separate issue/PR if it's a problem.)

• Issue: AIX build broken because of recent os.statx implementation. #140239