RFR 8236625 Remove writeable macro from JVM flags declaration

[Claes Redestad]

Nice cleanup, Ioi!

/Claes

On 2020-01-03 01:23, Ioi Lam wrote:
> https://bugs.openjdk.java.net/browse/JDK-8236625
> http://cr.openjdk.java.net/~iklam/jdk15/8236625-remove-writeable-flag-macro.v01/ 
> 
> 
> The "writeable" macro was used by commercial JVM flags, which have been
> removed from the JDK (see JDK-8205505). No flags in the JDK today use this
> macro. It should be removed.
> 
> I also inlined some accessor functions in the JVMFlag class for slightly
> more compact code.
> 
> Thanks
> - Ioi
> 
>