Based on suggestion from Fumihiro Bessho.

F_LOCK macro is not defined in android-ndk-r13.

available on Android API level 24, but the if_nameindex structure is not defined.

setattr() must not convert combined table into split table.

Issue #28383: __hash__ documentation recommends naive XOR to combine but this
is suboptimal. Update the doc to suggest to reuse the hash() method using a
tuple, with an example.

when a GC collection happens in another thread.

Original patch and report by Armin Rigo.

when a GC collection happens in another thread.

Original patch and report by Armin Rigo.

strxfrm() functions.

doesn't own its elements as limits.

doesn't own its elements as limits.