fixed a bug in merging public info from C modules. patch from Mark Vakoc

* doc/apibuild.py: fixed a bug in merging public info from
  C modules.
* win32/Makefile.msvc win32/configure.js: patch from Mark Vakoc
  the iconv option to configure.js didn't work, and
  added zlib option needed when linking xsltproc statically
Daniel