[10] RFR: 8178387: Reduce memory churn when creating java.lang.invoke entities

[Claes Redestad]

Hi,

another startup optimization for java.lang.invoke, this one collecting a 
set of small fixes I've been wanting to get done for a while, including:

- no need to generate the signature strings in 
BoundMethodHandle.makeCbmhCtor
- trusted MethodType lookups could be promoted without constructing new 
objects
- InvokerBytecodeGenerator: creation of className and sourceFile can be 
done lazily, which reduces String allocations in those cases where 
there's a pre-generated form to be found
- MethodType lookup done twice when looking up pregenerated members (oops!)
- A lot of vararg array creation during startup in various places. A 
larger rewrite could be warranted, but we can some startup gain by 
simply constant-izing oft-used constant arguments such as 
MethodType.invokerType

Webrev: http://cr.openjdk.java.net/~redestad/8178387/jdk.01/
Bug: https://bugs.openjdk.java.net/browse/JDK-8178387

Test: java.lang.invoke jtreg tests, verified each change in this patch 
(and JDK-8178384) reduces the amount of bytecode executed during lambda 
bootstrap.

Thanks!

/Claes