RFR(XS): 8229407: Avoid ConcurrentHashMap resizes during bootstrap

[Claes Redestad]

Hi core-libs,

analysis shows that a handful of small ConcurrentHashMaps used during
bootstrap is subject to some amount of resizing. Initializing these to
slightly larger values improves startup metrics measurably on default
images without regressing performance on minimal images.

Bug:    https://bugs.openjdk.java.net/browse/JDK-8229407
Webrev: http://cr.openjdk.java.net/~redestad/8229407/webrev.00/

Thanks!

/Claes