RFR: JDK-8171409 Create a smoother configure experience on macosx

[Magnus Ihse Bursie]

There are some "paper cuts" when running configure on macosx. They are 
trivial to fix and makes for a smoother experience.

Bug: https://bugs.openjdk.java.net/browse/JDK-8171409
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8171409-better-macosx-configure/webrev.01

/Magnus