Fix windows builds

Windows builds have the first arch set to x86 and the second set to
x86_64, and always prefers 32-bit.  Specify the 32-bit preference
manually, instead of relying on the architecture order for now.

Change-Id: I1900ec095e7773f68c0db293bfc48bd0815661b2
diff --git a/android/arch.go b/android/arch.go
index b653ce6..7ccd003 100644
--- a/android/arch.go
+++ b/android/arch.go
@@ -294,9 +294,13 @@
 		if multilib == "" {
 			multilib = module.base().commonProperties.Default_multilib
 		}
-		prefer32 := false
-		if class == Device {
+		var prefer32 bool
+		switch class {
+		case Device:
 			prefer32 = mctx.AConfig().DevicePrefer32BitExecutables()
+		case HostCross:
+			// Windows builds always prefer 32-bit
+			prefer32 = true
 		}
 		targets, err := decodeMultilib(multilib, targets, prefer32)
 		if err != nil {