Allow -lobjc and -framework IOKit in darwin host_ldlibs.

Bug: http://b/31321337
Test: mma of external/libusb on darwin
Change-Id: I1023a2a7ff1fdf809ac47104bca7b4171861abef
diff --git a/cc/config/x86_darwin_host.go b/cc/config/x86_darwin_host.go
index 1a4972e..09418c7 100644
--- a/cc/config/x86_darwin_host.go
+++ b/cc/config/x86_darwin_host.go
@@ -91,14 +91,19 @@
 		"10.11",
 	}
 
-	darwinAvailableLibraries = append(addPrefix([]string{
-		"c",
-		"dl",
-		"m",
-		"ncurses",
-		"pthread",
-		"z",
-	}, "-l"), "-framework CoreFoundation")
+	darwinAvailableLibraries = append(
+		addPrefix([]string{
+			"c",
+			"dl",
+			"m",
+			"ncurses",
+			"objc",
+			"pthread",
+			"z",
+		}, "-l"),
+		"-framework CoreFoundation",
+		"-framework IOKit",
+	)
 )
 
 const (