Need reviewers: 7043700: Regression for IcedTea builds (e.g. ALT_OUTPUTDIR)

[Kelly O'Hair]

Need reviewers. (Omair, you will want to verify this works for IcedTea).

Some background: this changeset:
  http://hg.openjdk.java.net/jdk7/jdk7/rev/47f6b7db1882
Created some issues for people setting ALT_OUTPUTDIR to a vanilla path like /tmp/foobar.
The expectation was that a debug build would show up in /tmp/foobar-debug, but it was showing
up in /tmp/OS-ARCH-debug.
The original changeset was mostly dealing with a Windows issue where you cannot just append
characters to an existing path and expect that path to be valid, so a technique of doing a /../ was used.

This fix tries to make it a bit more obvious what is going on, although I have to admit it's a confusing
situation regardless.

7043700: Regression for IcedTea builds
http://cr.openjdk.java.net/~ohair/openjdk7/jdk7-build-outdebug-7043700/webrev/

-kto