prov/efa: Get rid of noop instruction from empty #define

[a-szegel]

I was playing around on godbolt and saw that while (0) {} generates a noop instruction, but (void) 0; does not. Get rid of noop instructions from critical path without hurting the readability of the code.

[darrylabbate]

1. do {} while (0) (as some of the macros use) doesn't produce a nop. I'd prefer this over (void) 0.
2. Optimizations aren't enabled, but even if the compiler is producing a nop, it's likely for optimization/scheduling/alignment purposes, i.e. minimum sizes for fetch/decode chunks. IOW, I'd be curious if nops are being emitted unconditionally or only in cases where the compiler has a good reason to do so.
3. You should remove the trailing semicolons from the macro definitions.