rust: add ccToolchain to Module

The cc toolchain information is required when using cc.Stripper.
Move to a Module method to avoid importing the cc package everywhere.

Test: m nothing
Bug: 153430439
Change-Id: I497dcdff4e767ecb8b8688c73cf88850c302683d
diff --git a/rust/source_provider.go b/rust/source_provider.go
index e168718..755a369 100644
--- a/rust/source_provider.go
+++ b/rust/source_provider.go
@@ -38,7 +38,7 @@
 var _ SourceProvider = (*BaseSourceProvider)(nil)
 
 type SourceProvider interface {
-	GenerateSource(ctx android.ModuleContext, deps PathDeps) android.Path
+	GenerateSource(ctx ModuleContext, deps PathDeps) android.Path
 	Srcs() android.Paths
 	SourceProviderProps() []interface{}
 	SourceProviderDeps(ctx DepsContext, deps Deps) Deps
@@ -49,7 +49,7 @@
 	return android.Paths{sp.OutputFile}
 }
 
-func (sp *BaseSourceProvider) GenerateSource(ctx android.ModuleContext, deps PathDeps) android.Path {
+func (sp *BaseSourceProvider) GenerateSource(ctx ModuleContext, deps PathDeps) android.Path {
 	panic("BaseSourceProviderModule does not implement GenerateSource()")
 }