Allow 'sanitize' to be arch-specific.

The usecase here is system/core/liblog, which wants to turn off
sanitizer only for the target module, since the target sanitizers depend
on liblog.

Change-Id: I99141574a1c4c4847aa8a72bdcc88901fd9b01cd
diff --git a/cc/cc.go b/cc/cc.go
index 3aa068e..857235f 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -323,7 +323,7 @@
 	unused struct {
 		Native_coverage  bool
 		Required         []string
-		Sanitize         []string
+		Sanitize         []string `android:"arch_variant"`
 		Sanitize_recover []string
 		Strip            string
 		Tags             []string