The CodeGenerator sequence for Mod64/ModU64 is incorrectly using
32-bit operations.  Fix Mod64/ModU64 to use 64-bit divides to calculate
the remainder.

Fix disassembly for DLR, which was reading the wrong bits for the two
register operands.

R=jyan@ca.ibm.com,michael_dawson@ca.ibm.com,mbrandy@us.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1839813006

Cr-Commit-Position: refs/heads/master@{#35121}