Suffix our internal Xalan/Xerces dlls

[jng]

To allow for better hot-swappability of the GDAL binaries with alternative builds (eg. from gisinternals), our internal Xalan/Xerces dlls should be suffixed to avoid collision with possible equivalent dlls from whatever alternative build we replace our GDAL binaries with.

ie. Instead of building xerces as the default xerces-c_3_1.dll, build it as xerces-c_3_1fdo.dll. Similar for xalan

[jng]

In 8028:

Suffix "fdo" to our internal xerces/xalan dlls. This is to better support the scenario of replacing our internal gdal dll with an external copy built with expanded driver support (including some drivers that may depend on xerces/xalan), where we may risk potential ABI/runtime breakage as a result of overwriting our internal xerces/xalanc dlls with external copies that may not be built with the exact compiler settings or preprocessor defs as ours.

Fixes #986