Optimized include/*.h: (recursively) include all headers needed by
this .h file, but only those. Necessary fixes to a lot of .c files,
started optimizing "windows.h" away from some of them. Moved
GetCurrentTask prototype to wine/winbase16.h.

objects/metafile.c

diff --git a/objects/metafile.c b/objects/metafile.c
index 7cf534c..1da0384 100644
--- a/objects/metafile.c
+++ b/objects/metafile.c
@@ -8,13 +8,12 @@
 
 #include <string.h>
 #include <fcntl.h>
-#include "windows.h"
-#include "gdi.h"
+#include "wine/winbase16.h"
+#include "metafiledrv.h"
+#include "metafile.h"
 #include "bitmap.h"
 #include "file.h"
 #include "heap.h"
-#include "metafile.h"
-#include "metafiledrv.h"
 #include "toolhelp.h"
 #include "debug.h"