RFR 8216010: Change callers of build_u2_from() to call Bytes::get_Java_u2() instead

[Harold David Seigel]

Hi,

Please review this small fix for JDK-8216010.  The fix removes function 
build_u2_from() and changes its callers to call function 
Bytes::get_Java_u2().

Open Webrev: 
http://cr.openjdk.java.net/~hseigel/bug_8216010/webrev/index.html

JBS Bug:  https://bugs.openjdk.java.net/browse/JDK-8216010

The fix was regression tested by running Mach5 tiers 1 and 2 tests and 
builds on Linux-x64, Windows, and Mac OS X, running Mach5 tiers 3 - 5 on 
Linux-x64, and by running JCK-12 Lang and VM tests on Linux-x64.

Thanks, Harold