[8u20] Request for approval: 8033711 - An exception is thrown if using the "-classpath" option with no arguments

[Alexander Zuev]

Another backport from jdk9.

Bug: https://bugs.openjdk.java.net/browse/JDK-8033711
Fix pushed as: 
http://hg.openjdk.java.net/jdk9/dev/langtools/rev/95f9e1175e13
Fix applies without an issue to 
http://hg.openjdk.java.net/jdk8u/jdk8u-dev/langtools
Webrev is available at http://cr.openjdk.java.net/~kizune/8033971/webrev.00

/Alex