RFR(XS): 8015437: out-of-range SPARC assertion crash

[Morris Meyer]

Folks,

Could I get a review of this fix for an assembler code value out of 
range in the SPARC MacroAssembler?

The original code was incorrect in that it didn't check the size of the 
position offset.  This has been tested with JPRT.

         --mm

WEBREV - http://cr.openjdk.java.net/~morris/JDK-8015437.01
JBS - https://jbs.oracle.com/bugs/browse/JDK-8015437