cp#1000039 DOC import: ignore symbol charset of the symbol font

Otherwise characters unhandled by our OpenSymbol font (like Arabic 0-9
numbers) won't be rendered using an other font, as no other font
provides the symbol charset. Do this in
SwWW8ImplReader::GetFontParams(), where we already have font name ->
font family mappings for a few well-known fonts.

The DOCX filter does the same for quite some time, and that's how Arabic
numbers in text using the Symbol font were rendered, instead of little
rectangles.

(cherry picked from commit 8556cd881270823865662e9a7700da58d11c2785)

Conflicts:
	sw/qa/extras/ww8import/ww8import.cxx
	sw/source/filter/ww8/ww8par6.cxx

Change-Id: Ib794cac19ad7b073e39f3cbd7d4bad3994151c14