Fix: Rename macros as it conflicts with Mingw headers.
This is a known problem (http://caca.zoy.org/ticket/51). The easiest (and only) way to fix this is to rename the macros.
- DATADIR -> GIMPDATADIR
- SYSCONFDIR -> GIMPSYSCONFDIR
- DATADIR -> SYSDATADIR (tools/)
Edited by Salamandar