Support filegroups

filegroup is a module that contains a list of files, and can be used
to export files across package boundaries.  filegroups (and genrules)
can be referenced from srcs properties of other modules using the
syntax ":module".

Test: m -j
Change-Id: I3d6fc4819c0b4225b474e0ad42f0d947f55a5961

cc/cc.go

@@ -833,7 +833,7 @@ func (c *Module) depsToPaths(ctx android.ModuleContext) PathDeps {
 		cc, _ := m.(*Module)
 		if cc == nil {
 			switch tag {
-			case android.DefaultsDepTag:
+			case android.DefaultsDepTag, android.SourceDepTag:
 			case genSourceDepTag:
 				if genRule, ok := m.(genrule.SourceFileGenerator); ok {
 					depPaths.GeneratedSources = append(depPaths.GeneratedSources,

cc/compiler.go

@@ -29,6 +29,8 @@ import (
 
 type BaseCompilerProperties struct {
 	// list of source files used to compile the C/C++ module.  May be .c, .cpp, or .S files.
+	// srcs may reference the outputs of other modules that produce source files like genrule
+	// or filegroup using the syntax ":module".
 	Srcs []string `android:"arch_variant"`
 
 	// list of source files that should not be used to build the C/C++ module.
@@ -133,6 +135,8 @@ func (compiler *baseCompiler) compilerDeps(ctx DepsContext, deps Deps) Deps {
 	deps.GeneratedSources = append(deps.GeneratedSources, compiler.Properties.Generated_sources...)
 	deps.GeneratedHeaders = append(deps.GeneratedHeaders, compiler.Properties.Generated_headers...)
 
+	android.ExtractSourcesDeps(ctx, compiler.Properties.Srcs)
+
 	if compiler.hasSrcExt(".proto") {
 		deps = protoDeps(ctx, deps, &compiler.Proto)
 	}