RFR: 8198831: Lazy initialization of ValueConversions MethodHandles

[Claes Redestad]

Hi,

this patch makes the lookup of various MH in 
sun.invoke.util.ValueConversions lazy, realizing a tiny startup 
optimization to various apps.

Webrev: http://cr.openjdk.java.net/~redestad/8198831/jdk.00/
Bug:    https://bugs.openjdk.java.net/browse/JDK-8198831

Thanks!

/Claes