RFR: JDK-8140484: Vardeps broken when variable value contains '$'

[Erik Joelsson]

When I optimized the vardeps functionality in JDK-8136385, I caused a 
regression when the variable contained '$' characters. By reading the 
old value as a makefile using "include", variable substitution is 
applied. To work around this, dollar characters need to be escaped 
(doubled) prior to printing the variable value to the vardeps makefile.

This causes native libraries to be relinked every time they are 
incrementally built because of the "\$ORIGIN" string.

Also updating tests to cover this.

Bug: https://bugs.openjdk.java.net/browse/JDK-8140484
Webrev: http://cr.openjdk.java.net/~erikj/8140484/webrev.01/

/Erik