Bug 1480552 - handle aarch64 windows when determining MOZ_D3DCOMPILER_VISTA_DLL; r=ted.mielczarek

AArch64 Windows includes the necessary DLL in its default configuration,
so we don't need to bother locating it in the SDK.  We made need to
distribute an updated version that won't by on the system by default,
though, so we need some extra checking.

old-configure.in

@@ -2617,6 +2617,9 @@ i*86)
 x86_64)
   MOZ_D3D_CPU_SUFFIX=x64
   ;;
+aarch64)
+  MOZ_D3D_CPU_SUFFIX=arm
+  ;;
 esac
 
 dnl ========================================================
@@ -2648,6 +2651,9 @@ if test -n "$MOZ_ANGLE_RENDERER"; then
       if test -f "$MOZ_D3DCOMPILER_VISTA_DLL_PATH"; then
         AC_MSG_RESULT([Found MOZ_D3DCOMPILER_VISTA_DLL_PATH: $MOZ_D3DCOMPILER_VISTA_DLL_PATH])
         MOZ_HAS_WINSDK_WITH_D3D=1
+      elif test "$target_cpu" = "aarch64" -a "$MOZ_D3DCOMPILER_VISTA_DLL" = "d3dcompiler_47.dll"; then
+        AC_MSG_RESULT([AArch64 Windows includes d3dcompiler DLLs])
+        MOZ_D3DCOMPILER_VISTA_DLL_PATH=
       else
         AC_MSG_RESULT([MOZ_D3DCOMPILER_VISTA_DLL_PATH doesn't exist: $MOZ_D3DCOMPILER_VISTA_DLL_PATH])
         AC_MSG_ERROR([Windows SDK at "$WINDOWSSDKDIR" appears broken. Try updating to MozillaBuild 1.9 final or higher.])