Don't use assembler classes in code_generator.h.

The arm64 backend uses its own assembler and does not share
the same classes as the other backends. To avoid conflicts
or unnecessary mappings, just don't use those classes in the
shared part of the code generator.

Change-Id: I9e5fa40c1021d2e83a4ef14c52cd1ccd03f2f73d
8 files changed