hg: code-tools/jtreg: fix regex for build args; add test

[jonathan.gibbons at oracle.com]

Changeset: 577524fa83fe
Author:    jjg
Date:      2015-11-23 18:25 -0800
URL:       http://hg.openjdk.java.net/code-tools/jtreg/rev/577524fa83fe

fix regex for build args; add test

+ make/tests/BuildPatternTest.gmk
! src/share/classes/com/sun/javatest/regtest/BuildAction.java
+ src/share/test/javatest/regtest/BuildPatternTest.java