Generic configuration for generic system modules.

Config object includes a copy of itself for the generic configuration.
The generic configuration replaces any product-specific configurations
with the generic information.
When a module context gets Config() object, it returns the generic
configuration if the module sets use_generic_config to true. Otherwise,
Config() returns the original config object as before.

By adding `generic:"<value>"` annotation to the product variable, the
variables will be initialized with the <value> for the generic configs.
If the <value> is "unset", the variable will be unset.

The generic modules can be included in the shared system image to be
installed in multiple targets.

Bug: 361816274
Test: m nothing --no-skip-soong-tests
Change-Id: I15e4ade17ad1a8969f8e0e91d994b60545dc412f
diff --git a/android/module.go b/android/module.go
index a3fe837..87377cc 100644
--- a/android/module.go
+++ b/android/module.go
@@ -128,6 +128,9 @@
 	// WARNING: This should not be used outside build/soong/fsgen
 	// Overrides returns the list of modules which should not be installed if this module is installed.
 	Overrides() []string
+
+	// If this is true, the module must not read product-specific configurations.
+	UseGenericConfig() bool
 }
 
 // Qualified id for a module
@@ -507,6 +510,10 @@
 	// List of module names that are prevented from being installed when this module gets
 	// installed.
 	Overrides []string
+
+	// Set to true if this module must be generic and does not require product-specific information.
+	// To be included in the system image, this property must be set to true.
+	Use_generic_config *bool
 }
 
 // Properties common to all modules inheriting from ModuleBase. Unlike commonProperties, these
@@ -2588,6 +2595,10 @@
 	return m.commonProperties.Overrides
 }
 
+func (m *ModuleBase) UseGenericConfig() bool {
+	return proptools.Bool(m.commonProperties.Use_generic_config)
+}
+
 type ConfigContext interface {
 	Config() Config
 }