Move config into common and provide helper

Using ctx.Config().(Config) everywhere is a mouthful, and it is
inefficient to do the type assertion.  Put the Config interface into
the context, and provide an AConfig() to return the Config already
converted to the right type.

Change-Id: I301a1fd7d2a005580aabca7866a37c5d42ad8c69

common/module.go

@@ -20,16 +20,6 @@ import (
 	"github.com/google/blueprint"
 )
 
-type Config interface {
-	CpPreserveSymlinksFlags() string
-	SrcDir() string
-	IntermediatesDir() string
-	Getenv(string) string
-	EnvDeps() map[string]string
-	DeviceOut() string
-	HostOut() string
-}
-
 var (
 	DeviceSharedLibrary = "shared_library"
 	DeviceStaticLibrary = "static_library"
@@ -44,6 +34,7 @@ type androidBaseContext interface {
 	Host() bool
 	Device() bool
 	Debug() bool
+	AConfig() Config
 }
 
 type AndroidBaseContext interface {
@@ -299,7 +290,8 @@ func (a *AndroidModuleBase) DynamicDependencies(ctx blueprint.DynamicDependerMod
 	actx := &androidDynamicDependerContext{
 		DynamicDependerModuleContext: ctx,
 		androidBaseContextImpl: androidBaseContextImpl{
-			arch: a.commonProperties.CompileArch,
+			arch:   a.commonProperties.CompileArch,
+			config: ctx.Config().(Config),
 		},
 	}
 
@@ -314,7 +306,8 @@ func (a *AndroidModuleBase) GenerateBuildActions(ctx blueprint.ModuleContext) {
 	androidCtx := &androidModuleContext{
 		ModuleContext: ctx,
 		androidBaseContextImpl: androidBaseContextImpl{
-			arch: a.commonProperties.CompileArch,
+			arch:   a.commonProperties.CompileArch,
+			config: ctx.Config().(Config),
 		},
 		installDeps:        a.computeInstallDeps(ctx),
 		installFiles:       a.installFiles,
@@ -340,8 +333,9 @@ func (a *AndroidModuleBase) GenerateBuildActions(ctx blueprint.ModuleContext) {
 }
 
 type androidBaseContextImpl struct {
-	arch  Arch
-	debug bool
+	arch   Arch
+	debug  bool
+	config Config
 }
 
 type androidModuleContext struct {
@@ -382,10 +376,14 @@ func (a *androidBaseContextImpl) Debug() bool {
 	return a.debug
 }
 
+func (a *androidBaseContextImpl) AConfig() Config {
+	return a.config
+}
+
 func (a *androidModuleContext) InstallFileName(installPath, name, srcPath string,
 	deps ...string) string {
 
-	config := a.Config().(Config)
+	config := a.AConfig()
 	var fullInstallPath string
 	if a.arch.HostOrDevice.Device() {
 		// TODO: replace unset with a device name once we have device targeting