--- configure.orig      2017-11-17 16:05:28.000000000 -0700
+++ configure   2018-04-25 08:15:04.000000000 -0700
@@ -22447,7 +22447,7 @@
 
 fi
 
-for ac_header in limits.h unistd.h ucontext.h
+for ac_header in limits.h unistd.h
 do :
   as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
 ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"