Revamp how the version stuff is handled. Use the header file as the

Revamp how the version stuff is handled. Use the header file as the
original, and extract the numbers within the configure script.

* configure.in: extract the numbers from lib/expat.h

* Makefile.in: simplify the construction of DISTDIR

* lib/Makefile.in: no need to define the VERSION preprocessor symbol

* lib/expat.dsp: do not define VERSION (changed, but untested!)

* lib/xmlparse.c: revamp the XML_ExpatVersion() function

* lib/expat.h(.in): just ship the baby, rather than generating it