wininet: HTTP_HttpQueryInfoW deals with bytes, not characters so update the callers that have this wrong assumption.

instead of crashing so that when used with the replace flag it will
delete an existing value.

Fixes a regression found by Lei Zhang.

Based on a patch by Thomas Kho.

But report a failed test if a mandatory function is missing from it.

But report a failed test if a mandatory function is missing from it.
Also warn if the hardware capabilities force us to skip some tests.

tests: Add skip(), a function to warn that tests were skipped due to limitations of the environment or missing dependencies.