* src/misc/threads.c, src/misc/win32_specific.c, include/interface.h: fixed typos.
* configure.ac.in, modules/gui/gtk/gtk.c: Added a NEED_GTK_MAIN macro to the compiler
   flags for the gtk module. When this macro isn't defined, then the gtk module
   doesn't make use of the gtk_main module. I had to do this change because the
   gtk_main trick can't work on win32 and render the whole gtk interface unusable.