[xml] xmlGetLineNo still blocked at 65535 even if XML_PARSE_BIG_LINES is set

[fabrice nicol <fabrnicol gmail com>]

I'm experiencing recurring issues with xmlGetLineNo in DOM tree parsing.

Even though I set XML_PARSE_BIG_LINES as an option to xmlReadDoc or
xmlReadFile, the return value of xmlGetLineNo never exceeds 65535 (even
though it should by a large margin), in most of my XML files, except for
one. So the issue is unsystematic. Encoding of files is ISO-8859-1.

I tried to compile from github master source and increase the depth
ceiling value in xmlGetLineNoInternal (from 5 to 15, see commit
968a03a2e54f5bcf53089f5e3c8f790dbe0bf824) but to no avail. it also seems
that psvi fields are null in the cases at hand, which looks like a
possible cause.

I'm running an updated Gentoo GNU/Linux platform and platform compiler
is gcc-5.4.0, libxml2 version is 2.9.4-r1 and I also tried the lastest
github master code, same compiler, as well as gcc-6.3: no changes.

Is this a known issue or is there any hope of a way out? I found no
references to this in the archive either as of Aug. 2012.