Add FinalModule and VisitAllModuleVariants to ModuleContext

Allows modules to determine if they are the last of their variants
to build, and to visit each variant to collect shared information.

Change-Id: I396f0c9d43e0e9b1901822d6dd9c6ad6380ad582

blueprint/context.go

@@ -1205,7 +1205,6 @@ func (c *Context) generateModuleBuildActions(config interface{},
 						group:   group,
 					},
 					module: module,
-					primaryModule: group.modules[0],
 				},
 				scope: scope,
 			}

blueprint/module_ctx.go

@@ -128,6 +128,8 @@ type ModuleContext interface {
 	AddNinjaFileDeps(deps ...string)
 
 	PrimaryModule() Module
+	FinalModule() Module
+	VisitAllModuleVariants(visit func(Module))
 }
 
 var _ BaseModuleContext = (*baseModuleContext)(nil)
@@ -197,7 +199,6 @@ var _ PreModuleContext = (*preModuleContext)(nil)
 type preModuleContext struct {
 	baseModuleContext
 	module *moduleInfo
-	primaryModule *moduleInfo
 }
 
 func (m *preModuleContext) OtherModuleName(module Module) string {
@@ -280,7 +281,17 @@ func (m *moduleContext) AddNinjaFileDeps(deps ...string) {
 }
 
 func (m *moduleContext) PrimaryModule() Module {
-	return m.primaryModule.logicModule
+	return m.module.group.modules[0].logicModule
+}
+
+func (m *moduleContext) FinalModule() Module {
+	return m.module.group.modules[len(m.module.group.modules)-1].logicModule
+}
+
+func (m *moduleContext) VisitAllModuleVariants(visit func(Module)) {
+	for _, module := range m.module.group.modules {
+		visit(module.logicModule)
+	}
 }
 
 //