Revert "Remove product_is_iot."

This reverts commit 14fa562fbb.

Reason for revert: Broken build on 5772180

error: frameworks/av/media/utils/Android.bp:49:23: unrecognized property "product_variables.product_is_iot"

Bug: 138764596
Change-Id: I37944dfb974e4180a683361f514b404f92b943e5

android/variable.go

@@ -59,6 +59,17 @@ type variableProperties struct {
 			Cflags []string
 		}
 
+		// Product_is_iot is true for Android Things devices.
+		Product_is_iot struct {
+			Cflags       []string
+			Enabled      bool
+			Exclude_srcs []string
+			Init_rc      []string
+			Shared_libs  []string
+			Srcs         []string
+			Static_libs  []string
+		}
+
 		// treble_linker_namespaces is true when the system/vendor linker namespace separation is
 		// enabled.
 		Treble_linker_namespaces struct {
@@ -251,6 +262,8 @@ type productVariables struct {
 
 	Override_rs_driver *string `json:",omitempty"`
 
+	Product_is_iot *bool `json:",omitempty"`
+
 	Fuchsia *bool `json:",omitempty"`
 
 	DeviceKernelHeaders []string `json:",omitempty"`