patch 8.1.0766: various problems when using Vim on VMS

Problem:    Various problems when using Vim on VMS.
Solution:   Various fixes. Define long_long_T. (Zoltan Arpadffy)
diff --git a/src/xdiff/xdiff.h b/src/xdiff/xdiff.h
index a8bc1dc..783dc9d 100644
--- a/src/xdiff/xdiff.h
+++ b/src/xdiff/xdiff.h
@@ -108,7 +108,11 @@
 	long bsize;
 } bdiffparam_t;
 
-#include "../vim.h"
+#ifdef VMS
+# include "[]vim.h"
+#else
+# include "../vim.h"
+#endif
 
 #define xdl_malloc(x) lalloc((x), TRUE)
 #define xdl_free(ptr) vim_free(ptr)