Make ncurses-config report the correct directory for ncurses.h.

Index: configure
===================================================================
--- configure.orig
+++ configure
@@ -5336,6 +5336,7 @@ else
 fi;
 echo "$as_me:5337: result: $with_overwrite" >&5
 echo "${ECHO_T}$with_overwrite" >&6
+WITH_OVERWRITE="$with_overwrite"
 
 echo "$as_me:5340: checking if external terminfo-database is used" >&5
 echo $ECHO_N "checking if external terminfo-database is used... $ECHO_C" >&6