Output compile errors when signed integer types are used on functions
where the answer might've been a complex number but that functionality hasn't
been implemented.
This applies to sqrt, log, log2, log10 and ln.
A test which used a signed integer was also changed to use an unsigned
integer instead.
This change was mostly made with `zig fmt` and this also modified some whitespace. Note that in some files, `zig fmt` produced incorrect code, so the change was made manually.