Revert "Simplify arch target handling"

This reverts commit 6713fb26cbcadf525cd75e47d7d0cbc23d282b3e.

Change-Id: Ic473cea2563b0b37dc08b0bc5d3a0ac8c4b6afe6
diff --git a/cc/x86_darwin_host.go b/cc/x86_darwin_host.go
index 987b1dd..f3cf1c9 100644
--- a/cc/x86_darwin_host.go
+++ b/cc/x86_darwin_host.go
@@ -280,6 +280,6 @@
 }
 
 func init() {
-	registerToolchainFactory(android.Darwin, android.X86, darwinX86ToolchainFactory)
-	registerToolchainFactory(android.Darwin, android.X86_64, darwinX8664ToolchainFactory)
+	registerHostToolchainFactory(android.Darwin, android.X86, darwinX86ToolchainFactory)
+	registerHostToolchainFactory(android.Darwin, android.X86_64, darwinX8664ToolchainFactory)
 }