enable readline by disabling conio

conio does not work reliable when editing a bconsole line.
Use readline instead, which should be available on all relevant
platforms.

scripts/regress-config.in

@@ -30,7 +30,7 @@ fi
     --with-plugindir=${1}/bin/plugins \
     --enable-smartalloc \
     --enable-lockmgr \
-    --disable-readline \
+    --disable-conio \
     --with-working-dir=${1}/working \
     --with-archivedir=${1}/tmp \
     --with-dump-email=${EMAIL} \