Request for Review (xs) - 8024945: Remove check on minimum size of MetaspaceSiz

[Jon Masamitsu]

https://bugs.openjdk.java.net/browse/JDK-8024945

Previous to this change the smallest MetaspaceSize value allowed
was 256k.  There is not reason for the restriction so this change
removes it.  A very small MetaspaceSize  (even 0) does not cause
a problem because during initialization a GC is not triggered unless
the Metaspace needed grows beyond MaxMetaspaceSize.

http://cr.openjdk.java.net/~jmasa/8024945/webrev.00/

Tested with -XX:MetaspaceSize=0.  General testing with gc_test_suite.

Thanks.

Jon