hg: jdk9/sandbox/langtools: Fix langtools' version strings and adjust tests accordingly.

[kumar.x.srinivasan at oracle.com]

Changeset: 26723745dcc4
Author:    ksrini
Date:      2015-04-07 14:13 -0700
URL:       http://hg.openjdk.java.net/jdk9/sandbox/langtools/rev/26723745dcc4

Fix langtools' version strings and adjust tests accordingly.

! make/gensrc/GensrcCommon.gmk
! src/java.compiler/share/classes/javax/lang/model/SourceVersion.java
! test/tools/javac/options/modes/SourceTargetTest.java