misc: Fix issues flagged by gcc 6

misc: Fix issues flagged by gcc 6

A few warnings (and thus errors) pop up after being added to -Wall:

1. -Wmisleading-indentation

In the auto-generated code there were instances of if/else blocks that
were not indented to gcc's liking. This is addressed by adding braces.

2. -Wshift-negative-value

gcc is clever enougn to consider ~0 a negative constant, and
rightfully complains. This is addressed by using mask() which
explicitly casts to unsigned before shifting.

That is all. Porting done.