[10] RFR: 8175233: Remove LambdaForm.debugName

[Claes Redestad]

Hi,

the LambdaForm.debugName field is useful for debugging, but names
are generated and retained in this field also for production code, which
is then used to name generated methods and classes.

This patch suggests to extract this field and make the debug name an
external mapping that is only generated (and used) when actually debugging,
while using LambdaForm.Kinds to guide the naming of classes and methods
generated in production mode.

This also fixes(?) a subtle bug that when transforming a LambdaForm using
LambdaFormEditors the debugName was retained through all transformations,
which leads to confusing/surprising results (since many transformations 
starts
out with a BMH.reinvoker and is then transformed via editor manipulations,
most generated forms appear to be BMH.reinvokers when in fact they aren't).

Bug:
https://bugs.openjdk.java.net/browse/JDK-8175233

Webrevs:
http://cr.openjdk.java.net/~redestad/8175233/jdk.01/
http://cr.openjdk.java.net/~redestad/8175233/hotspot.01/

Testing:
- Pre-checkin testing on all platforms
- Locally tested java.lang.invoke tests with and without 
-Djava.lang.invoke.MethodHandle.DEBUG_NAMES=true
- Ensured -Djava.lang.invoke.MethodHandle.DUMP_CLASS_FILES=true behaves 
as intended
- Made sure the changes don't clash with JDK-8172298

Thanks!

/Claes