The patch puts in "Misc/NEWS.d/next/Core and Builtins/2017-10-11-10-42-02.bpo-31748.oaEZcq.rst":

+Support configure with -Wall by avoiding unused variables.

but likely means "-Werror" (or both)

Different people generate ./configure different ways.  Some insert runstatedir in configure, others don't.  E.g. on 14 April 2017 runstatedir was added to configure, on 9 June it was removed from configure, on 29 June it was added to configure.  It needs to be clarified once forever, whether runstatedir belongs to configure or not and then everybody has to stick to this, in order to avoid useless changes in the version control.