Fix 'Exception in thread "main" java.lang.AbstractMethodError:'

When running with OpenJDK 8 (openjdk version "1.8.0_45-internal") on
module messaging, sometimes an odd exception is caught in main:
Exception in thread "main" java.lang.AbstractMethodError:
java.lang.Exception.getMessage()Ljava/lang/String;
at proguard.ProGuard.main(ProGuard.java:519)

It's not 100% reproducible. But it's certain to happen if you run the
same ProGuard tasks in parallel (e.g. x40).

The exception runtime type is actually
java.lang.ArrayIndexOutOfBoundsException, which I tracked down to
raise from MappingPrinter.visitLineNumberTableAttribute().
It's strange that the exception object is in a weird state that
e.printStatckTrace() throws java.lang.AbstractMethodError.
Other people have seen similar things too:
http://stackoverflow.com/questions/6777710/abstractmethoderror-on-calling-exception-printstacktrace

Using temparary variables low/high fixes the crash.
It seems to be an OpenJDK 8 bug.

Rebuilt the jar files by running build/build.sh.

Bug: 26274804
Change-Id: I773023b2dc57bd048c6781aded84e0c0df923a90