RFR: 8253636: C2: Adjust NodeClasses::_max_classes

[Roberto Castañeda Lozano]

On Tue, 29 Sep 2020 09:57:38 GMT, Roberto Castañeda Lozano <github.com+8792647+robcasloz at openjdk.org> wrote:

> Update `NodeClasses::_max_classes` to the max class id within the enumeration. Update comment and assertion to reflect
> that `NodeClasses` uses now 32 bits after the addition of `Opaque1` in JDK-8229495.

Update NodeClasses::_max_classes to the max class id within the
enumeration. Update comment and assertion to reflect that NodeClasses uses now
32 bits after the addition of Opaque1 in JDK-8229495.

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PR: https://git.openjdk.java.net/jdk/pull/397