RFR: JDK-8221179: Zero builds fail when linking with gold and bundling libffi.so

[Erik Joelsson]

This patch adds a missing RPATH to libjvm.so which is needed when 
bundling libffi.so for zero builds. The rpath is only added when 
building zero and bundling of libffi is enabled. When linking with bfd 
(the old binutils linker), it seems that the rpath of the library that 
loaded libjvm.so (libjli.so) is implicitly still active, so this isn't a 
problem. At Oracle we recently switched to the gold linker and then the 
implicit rpath is no longer in effect.

Bug: https://bugs.openjdk.java.net/browse/JDK-8221179

Webrev: http://cr.openjdk.java.net/~erikj/8221179/webrev.01/

/Erik