Small changes made according to static analyzer results

[fuzun]

I did not want to to change type of feature variables since it seems that they are getting accessed directly by other projects but could not find any other solution. Making them bool would probably break portability. Other option might be defining TRUE as -1 then modifying related parts.

Feature variable returning functions (Get...FeaturesEnumValue) are kept intact as automatic casting should not cause any problem. And because variables are all aligned, there should be no warning because of this casting in compilers other than VS. (I did not test though).

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[gchatelet]

So unfortunately this PR is changing the API and may break client code.
I'm willing to pull everything in but the int -> unsigned intmodification (we would also need to modify the other platforms arm, aarch64, power ...). Can you revert this part?

[fuzun]

I have realized that bit_utils.h is internal so made some changes there instead of structs. Still not the best but I could not think any other solution without changing structures.

[gchatelet]

Let's set 58a232c aside for now. I have to think this through. The rest of the PR is welcome though.

[fuzun]

Yeah it is definitely not the best way since something like x == TRUE can result in absolute mess if TRUE is used instead of true mistakenly.

I could not think any other high level change to fix this so I agree that this commit should be dropped in favor of a potential lower level change later.

I'm reverting this commit now.

[gchatelet]

Thx a lot for your patience and for contributing to cpu_features.
Can you open a bug about the bool correctness issue so I keep it on my radar?

[fuzun]

Sure!
Issue: #43