Removed a lot of occurences of windows.h (and added necessary other
includes).

diff --git a/loader/pe_resource.c b/loader/pe_resource.c
index 9839b69..0e2ab76 100644
--- a/loader/pe_resource.c
+++ b/loader/pe_resource.c
@@ -12,8 +12,8 @@
 
 #include <stdlib.h>
 #include <sys/types.h>
+#include "wine/winestring.h"
 #include "wintypes.h"
-#include "windows.h"
 #include "pe_image.h"
 #include "module.h"
 #include "heap.h"