* winsup.h: Eliminate inclusion of most of the cygwin .h files. Use .h files

only in sources which require them.
* Makefile.in: Generate dependencies with -MD option.

winsup/cygwin/dlfcn.cc

@@ -15,6 +15,9 @@ details. */
 #include <ctype.h>
 #include "dlfcn.h"
 #include "dll_init.h"
+#include "fhandler.h"
+#include "path.h"
+#include "thread.h"
 
 #define _dl_error _reent_winsup()->_dl_error
 #define _dl_buffer _reent_winsup()->_dl_buffer