hg: jdk/sandbox: More path fixes. Make it work again on non-windows.

[magnus.ihse.bursie at oracle.com]

Changeset: d346b729887a
Author:    ihse
Date:      2020-07-03 01:44 +0200
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/d346b729887a

More path fixes. Make it work again on non-windows.

! make/autoconf/basic.m4
! make/autoconf/basic_windows.m4
! make/autoconf/util_paths.m4