Blender Git Loki

make deps: avoid running pdflatex as part of building Theora

On machines with pdflatex installed, this is run to build Theora.pdf.
Unfortunately this process breaks, at least on my Ubuntu 18.04 LTS
system. By setting `HAVE_PDFLATEX=no` (or any other value that is not
"yes") this can be avoided. I don't think that it's important to have
this PDF file built anyway, as it's not a dependency of Blender itself.