Reorganise the functions doing wfProfileOut and returning on all if branches.

Reorganise the functions doing wfProfileOut and returning on all if branches.

Makes life easier for static analysis, since they don't need to
handle if the end of a function where a wfProfileOut was not called
was reachable or not.

It is recommended to review this change ignoring whitespaces
(specially for includes/parser/Tidy.php)

Also documented the rationale for the elseif chain in UploadBase::detectVirus()

Change-Id: Ic4f65937fa9e6f926d8fcfd670e3b0e99e06eefc