Need reviewer: ant 1.7.1 or newer needed

[Kelly O'Hair]

Need reviewer: ant 1.7.1 or newer needed

This changes the minimum required ant version to 1.7.1 and also makes  
it a fatal sanity error
to try and use anything older.
The ant 1.7.1 release was done in July 2008 and is a well known stable  
ant release.

7016976: Documentation for required ant version  on JDK7 builds on  
Solaris 10 and Solaris 11
http://cr.openjdk.java.net/~ohair/openjdk7/jdk7-build-ant171/webrev/

-kto

P.S. Ant binary bundles can be found at http://archive.apache.org/dist/ant/binaries/