Make robolectric runtimes a host module

I931f9145f1ced21a9f86d647cfbb6d2b645b4f18 made robolectric_android-all-stub
empty, breaking running robolectric tests packaged by Soong.
To enable using robolectric-host-android_all instead, make the
runtimes module a host module.

Also remove the empty robolectric_android-all-stub dependency.

Test: m checkbuild
Change-Id: Idc158d84fd8b6d98d824a6bdc8be297ac43ec2f2
diff --git a/java/robolectric.go b/java/robolectric.go
index ec112bc..04fc117 100644
--- a/java/robolectric.go
+++ b/java/robolectric.go
@@ -31,7 +31,6 @@
 }
 
 var robolectricDefaultLibs = []string{
-	"robolectric_android-all-stub",
 	"Robolectric_all-target",
 	"mockito-robolectric-prebuilt",
 	"truth-prebuilt",
@@ -99,7 +98,8 @@
 
 	ctx.AddVariationDependencies(nil, roboCoverageLibsTag, r.robolectricProperties.Coverage_libs...)
 
-	ctx.AddVariationDependencies(nil, roboRuntimesTag, "robolectric-android-all-prebuilts")
+	ctx.AddFarVariationDependencies(ctx.Config().BuildOSCommonTarget.Variations(),
+		roboRuntimesTag, "robolectric-android-all-prebuilts")
 }
 
 func (r *robolectricTest) GenerateAndroidBuildActions(ctx android.ModuleContext) {
@@ -335,7 +335,7 @@
 func robolectricRuntimesFactory() android.Module {
 	module := &robolectricRuntimes{}
 	module.AddProperties(&module.props)
-	android.InitAndroidArchModule(module, android.DeviceSupported, android.MultilibCommon)
+	android.InitAndroidArchModule(module, android.HostSupportedNoCross, android.MultilibCommon)
 	return module
 }
 
@@ -365,6 +365,10 @@
 }
 
 func (r *robolectricRuntimes) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	if ctx.Target().Os != ctx.Config().BuildOSCommonTarget.Os {
+		return
+	}
+
 	files := android.PathsForModuleSrc(ctx, r.props.Jars)
 
 	androidAllDir := android.PathForModuleInstall(ctx, "android-all")