FindJNI: Support biarch installations (#14541)

On biarch architecture, CMAKE_SYSTEM_PROCESSOR might be a 64bit one
while the system 32bit one. Take this into consideration while looking
for Java library directory.

Bug-Debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=718290
Merge topic 'FindJNI-biarch' into next

cde56c1 FindJNI: Support biarch installations (#14541)