RFR: JDK-8177634 Fix for 8175307 may cause linker errors on OS X 10.9

Wed Mar 29 08:33:04 UTC 2017

Since JDK-8175307 was fixed we started seeing failures like this on OS X 
10.9 systems:

dyld: Library not loaded: @rpath/libjvm.dylib
   Referenced from:
/opt/jprt/T/P1/144150.mgerdin/bundles/testBundle/hotspot/gtest/server/gtestLauncher 

   Reason: image not found
make[2]: *** [hotspot_gtestserver] Trace/BPT trap: 5 (core dumped)

The reason was that JDK-8175307 replaced -Wl,-rpath, at loader_path/. with 
-Wl,-rpath, at loader_path in some cases. This works well on modern macOS 
but fails on OS X 10.9 and earlier.

This patch restores the old behavior of adding /. if no other path is given.

I have verified that it solves the problem on 10.9, and that is does not 
break on newer macOS. I have also verified the fix on all platforms on JPRT.

I intend to get approval to push this into JDK9.

The final form of the patch was contributed by David DeHaven.

Bug: https://bugs.openjdk.java.net/browse/JDK-8177634
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8177634-fix-loader_path-on-macos/webrev.01

/Magnus