RFR 8144841: Add a sample for pluggable dynalink linker for stream property on arrays and a REAMDE for linker samples

[Sundararajan Athijegannathan]

Please review http://cr.openjdk.java.net/~sundar/8144841/ for 
https://bugs.openjdk.java.net/browse/JDK-8144841

Adding a README for dynalink samples as Marcus suggested earlier.
Thanks,
-Sundar