
These files are taken from Expat, Release 2.2.6.

The source files have been slightly modified in order to fit them into this
build system. The changes that were made are:

 - Source files now only include config.h (instead of a choice of
   expat_config.h, winconfig.h, etc.).

 - expat_external.h includes harp_expat_mangle.h to name mangle all
   public symbols.

 - Add '#undef' for uint8_t/uint32_t/uint64_t in siphash.h to prevent
   compilation problems on Windows.

 - internal.h includes windows.h (since it can't be included in config.h).
