[gtk/gtk-3-24] win32/detectenv-msvc.mak: Add linker flag for ARM64

[Chun-wei Fan <fanchunwei src gnome org>]

commit 935691f94cddb1f5c55db5f414cb9ff992d8e43f
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Tue Feb 23 17:31:24 2021 +0800

    win32/detectenv-msvc.mak: Add linker flag for ARM64
    
    This prepares things better for ARM64 (aarch64) Windows builds, to make things
    more complete and comparable to x64 and x86 builds.

 win32/detectenv-msvc.mak | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/win32/detectenv-msvc.mak b/win32/detectenv-msvc.mak
index 22facfee23..29b73d88bf 100644
--- a/win32/detectenv-msvc.mak
+++ b/win32/detectenv-msvc.mak
@@ -77,6 +77,8 @@ CFLAGS_ADD = /MDd /Od $(CFLAGS_BASE)
 
 !if "$(PLAT)" == "x64"
 LDFLAGS_ARCH = /machine:x64
+!elseif "$(PLAT)" == "arm64"
+LDFLAGS_ARCH = /machine:arm64
 !else
 LDFLAGS_ARCH = /machine:x86
 !endif