Remove ModuleBase.prefer32.

It became obsolte by If96cccbd82ba1311165d61c947c928c6e7cd5593 and
Iaaac16ae171c06d90d04d7cac11789d3f39b8d99

Test: TreeHugger
Change-Id: Ifc8f28663b480ef5aff93a54040339ef080072c9

android/arch.go

@@ -616,16 +616,8 @@ func archMutator(bpctx blueprint.BottomUpMutatorContext) {
 		osTargets = []Target{osTargets[0]}
 	}
 
-	// Some modules want compile_multilib: "first" to mean 32-bit, not 64-bit.
-	// This is used for HOST_PREFER_32_BIT=true support for Art modules.
-	prefer32 := false
-	if base.prefer32 != nil {
-		prefer32 = base.prefer32(mctx, base, os)
-	}
-	if os == Windows {
-		// Windows builds always prefer 32-bit
-		prefer32 = true
-	}
+	// Windows builds always prefer 32-bit
+	prefer32 := os == Windows
 
 	// Determine the multilib selection for this module.
 	multilib, extraMultilib := decodeMultilib(base, os.Class)