Rename `GetInstructionSet{,Code}Alignment`.

Update the `GetInstructionSetAlignment()` function name to
`GetInstructionSetCodeAlignment()` in line with renames from
    https://android-review.googlesource.com/2229498 .
Move the function to `instruction_set.h` and change the
handling of unknown instruction sets to the approach used
in other functions in the header file.

Test: buildbot-build.sh --target
Change-Id: I8239b94b56bf24f4e99a2d72ba10ec1f5a055d36
10 files changed