Address mistakes in inline functions cpp

[Rageking8]

Fixes #4871

Tidy up some of the earlier examples, augmented the multiply example to be more explicit about the differences when using a function macro like a proper function. For the last example, there seems to be UB with sqr(c++) which expands to ((c++) * (c++)), hence I wrapped it away into a function and added the part about the inline function square.

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[Court72]

@TylerMSFT

Can you review the proposed changes?

When the changes are ready for publication, add a #sign-off comment to signal that the PR is ready for the review team to merge.

#label:"aq-pr-triaged"
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[TylerMSFT]

Good stuff - thanks @Rageking8!

[TylerMSFT]

#sign-off