patch 9.1.1499: MS-Windows: no indication of ARM64 architecture

Problem:  MS-Windows: no indication of ARM64 architecture
Solution: Add ARM64 to version output and include in nsis installer
          (RestorerZ)

related: vim/vim-win32-installer#381
closes: #17642

Signed-off-by: RestorerZ <restorer@mail2k.ru>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/nsis/Make_mvc.mak b/nsis/Make_mvc.mak
index c5aff15..8350082 100644
--- a/nsis/Make_mvc.mak
+++ b/nsis/Make_mvc.mak
@@ -46,6 +46,10 @@
 MKNSISFLAGS = $(MKNSISFLAGS) /DWIN64=$(WIN64)
 !ENDIF
 
+!IFDEF ARM64
+MKNSISFLAGS = $(MKNSISFLAGS) /DARM64=$(ARM64)
+!ENDIF
+
 !IFDEF INCLUDE_LIBGCC
 MKNSISFLAGS = $(MKNSISFLAGS) /DINCLUDE_LIBGCC=$(INCLUDE_LIBGCC)
 !ENDIF