[8u-dev]: 8029797: Let jprt run configure when building

[Mikael Vidstedt]

All,

Please review this backport of 8029797 from jdk9 to jdk8u-dev. The 
change in question moves the responsibility of calling configure from 
the the Jprt.gmk Makefile to JPRT. It was originally integrated to jdk9 
by Erik in January and has been use for all of the jdk9 development ever 
since.

Bug: https://bugs.openjdk.java.net/browse/JDK-8029797
jdk9 changeset: http://hg.openjdk.java.net/jdk9/dev/rev/c3c75eda6606
jdk8u webrev: 
http://cr.openjdk.java.net/~mikael/webrevs/8029797-8udev/webrev/

Thanks,
Mikael