[9] RFR (S): 8056926: Improve caching of GuardWithTest combinator

[Vladimir Ivanov]

http://cr.openjdk.java.net/~vlivanov/8056926/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8056926

Cache GuardWithTest per erased to basic types signature.

GWT shape is made friendly to sharing:
   * GWT MH is implemented as BMH which stores 3 method handles
   * LF loads them from the associated MethodHandle

Testing: jdk/java/lang/invoke, jdk/java/util/streams, nashorn, octane w/ 
"-ea -esa" and COMPILE_THRESHOLD={0,30}.

Reviewed-by: vlivanov, ?
Contributed-by: john.r.rose at oracle.com

Thanks!

Best regards,
Vladimir Ivanov