RFR(S): 8078017: Introduce hotspot_basicvmtest

[Mikael Vidstedt]

Please review this change which introduces a new test target called 
hotspot_basicvmtest. The new test target runs the union of the 
hotspot_client, hotspot_minimal and hotspot_server test targets. The 
change also updates JPRT to use the new target instead of the old ones.

Bug: https://bugs.openjdk.java.net/browse/JDK-8078017
Webrev (top repo): 
http://cr.openjdk.java.net/~mikael/webrevs/8078017/webrev.00/hotspot/webrev/
Webrev (hotspot repo): 
http://cr.openjdk.java.net/~mikael/webrevs/8078017/webrev.00/top/webrev/

Motivation:

Running all the three vm option tests as a single test target reduces 
the per-test setup cost while still providing the same test coverage.

Description:

Most of the changes are mechanical changes to the jprt.properties file 
to use the new makefile target. The new test target is implemented in 
the hotspot/test/Makefile. It discovers which jvm variants (client, 
minimal and/or server) are available by looking for the corresponding 
directories in the JDK under test. The exact directory within JDK where 
the JVM directories reside differ between the different platforms, but 
they all follow the same general pattern.

Tested locally and in JPRT.

Cheers,
Mikael