. Passing invalid characters to ''base_convert()'', ''bindec()'', ''octdec()''
and ''hexdec()'' will now generate a deprecation notice. The result will
still be computed as if the invalid characters did not exist. Leading and
trailing whitespace, as well as prefixes of type 0x (depending on base)
continue to be allowed.

It's not possible to find programmatically these cases. So all we can do is to fix those we are aware about (automated + manual testing).

Whenever more cases are detected, they will need to be fixed. In any case, code will continue working the same, because the behavior (ignore incorrect chars) has not changed.

Example: https://3v4l.org/mrfun

Fixes here have to go both to 38_STABLE and master (part of the php74 epic).