RFR: JDK-8137014 Various improvements in build infrastructure

[Magnus Ihse Bursie]

As a result of the recent work in the build-infra sandbox, here is a 
batch of improvements and fixes to the build-infra structure. Some of 
these are needed to support the conversion of the building of an Oracle 
internal test framework, while other are general improvements.

A list of fixes included:

* Fix for LogFailures which did not work if $1 had a / in it's name.

* Improved vardeps handling in JavaCompilation.

* Improved LOG=info logging from SetupNativeCompilation.

* Add a COMP_DIR option to COMPARE_BUILD, to allow comparison of two 
specific subdirectories (and not only normal images).

* Improved error reporting in case of incorrect usage of paths to 
SetupJavaCompilation and SetupNativeCompilation.

* Improvements of the compare script for build result comparisions, 
including two new options --strip and --sort-symbols, which
will strip all binaries before comparing, and sort all native symbols 
(per library) before comparing them, respectively.

* Properly handle Java manifest files given by MANIFEST argument even 
with linebreak issues

* In JavaCompilation, add KEEP_DUPS argument (Do not remove duplicate 
file names from different source roots).

Bug: https://bugs.openjdk.java.net/browse/JDK-8137014
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8137014-build-infra-improvements/webrev.01

/Magnus