RFR: JDK-8210931 JLI and launchers normalization and cleanup

[Magnus Ihse Bursie]

There's a lot of weird stuff going on with libjli and the launchers. 
Most of it stems from the old build system, which was just copied 
verbatim into the new build system. This is the final part of getting 
JLI to behave like most other libraries.

This patch will:
* store libjli in the standard lib directory, not in a "jli" subdirectory.
* remove dead code for filtering ergo files, which do no longer exist
* use file extension to show type (ObjectiveC), rather than -x objective-c.
* use more common  constructs in setting up the native compilation 
arguments.
* clean out unused flags and arguments.

Bug: https://bugs.openjdk.java.net/browse/JDK-8210931
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8210931-jli-normalization/webrev.01

/Magnus