RFR: 8159613: [Findbugs] various warnings reported for JVMCI sources

[Doug Simon]

Please review this webrev which addresses all the issues[1] identified by FindBugs in the JVMCI Java code. A significant number of issues related to exposing array fields. For example:

M V EI: jdk.vm.ci.hotspot.sparc.SPARCHotSpotRegisterConfig.getCallerSaveRegisters() may expose internal representation by returning SPARCHotSpotRegisterConfig.callerSaveRegisters  At SPARCHotSpotRegisterConfig.java:[line 187]
M V EI: jdk.vm.ci.amd64.AMD64.getAvailableValueRegisters() may expose internal representation by returning AMD64.valueRegistersSSE  At AMD64.java:[line 252]

These have been addressed by either creating an immutable array wrapper classes (e.g. RegisterArray) or by documenting intentional mutability and applying @SuppressFBWarnings where necessary.

https://bugs.openjdk.java.net/browse/JDK-8159613
http://cr.openjdk.java.net/~dnsimon/8159613/

-Doug

[1] http://cr.openjdk.java.net/~dnsimon/8159613/FindBugsIssues.txt