Core/Common/VideoCommon: Fix some weird (!eof) logic.

[jordan-woyak]

Logic of the form, while (!eof), is almost always "wrong".

The success of the actual read needs to be tested, which may or may not trigger eof.

The three pieces of code I found with while (!eof) did also test that the read was successful, so the behavior was correct, but the eof checks were still unnecessary and made the loops awkward.

[Dentomologist]

We should return in.eof() at the end of the function instead of just true in case there was a read error (and get rid of the redundant close).

[jordan-woyak]

I don't think so. So long as the file can be opened (which is checked by if (in.fail()) above), while (std::getline(in, line_str)) will process lines until no more lines can be read, and then we are done, and it was successful. eof is not relevant. That's the point of this PR. ;) but, yeah, the close is superfluous and could be removed.

[AdmiralCurtiss]

Well... technically, the read could fail mid-file if you have a disk error, or your USB device gets disconnected, or something like that. In that case you'd want to return false and not true, since you don't want the caller to proceed with half a file.