fbt: Fix compiler warnings in CDDL fbt sources.

[khng]

Summary

Mark unused arguments.

Avoid shadowing global variables.

Void cast the return of functions where the return value is
intentionally being ignored.

Handle signed/unsigned mismatches.

Obtained from: Juniper Networks, Inc.
MFC after: 1 week

[zlei]

sys/cddl/dev/fbt/fbt.c

442

The global var version is defined as extern char version[]; in sys/sys/system.h, and the implementation is generated by sys/conf/newvers.sh .

Since the global one has a different type char [], I think the shadowing should be easily caught by modern compilers.

PS: I'd prefer the shorter one ver rather than vers. The latter sounds like multiple version[s].

907

The parameter name should be unsigned. No idea why it was defined as int.
@markj
Do you have any clues ?

[markj]

sys/cddl/dev/fbt/fbt.c

907

I don't know offhand why it's signed. I can't see any (ab)use of that property.

Really the parameter should be size_t.