Allow java modules to use filegroups

Using filegroups requires calling ExtractSourcesDeps from the deps
mutator.

Test: m -j checkbuild
Change-Id: I7b6c6ce0075e4a703d28085a3965f11d9bb46315

java/java.go

@@ -200,6 +200,8 @@ func (j *Module) deps(ctx android.BottomUpMutatorContext) {
 	}
 	ctx.AddDependency(ctx.Module(), libTag, j.properties.Libs...)
 	ctx.AddDependency(ctx.Module(), staticLibTag, j.properties.Static_libs...)
+
+	android.ExtractSourcesDeps(ctx, j.properties.Srcs)
 }
 
 func (j *Module) aidlFlags(ctx android.ModuleContext, aidlPreprocess android.OptionalPath,