Fix: build error when a lib with stubs is included in an APEX

apex { name: "foo", native_shared_libs: ["mylib"] }
cc_library { name: "mylib", shared_libs: ["other_lib"],
             stubs: { versions: ["1"]}, }

This is causing build error due to missing variant for other_lib.
This is happening because the stubs variant of mylib is added to apex
foo instead of the non-stubs variant. Because stubs variant does not
have any further dependencies, other_lib is not included to the APEX and
is not built for it.

Fixing this issue by specifying the version variant when adding a lib to
the dependency of an APEX, so that non-stub variant of the lib is
depended on.

Test: m (apex_test updated)
Change-Id: I972b6dcbce11942f83a76212715ba915534ec3df

apex/apex.go

@@ -367,6 +367,7 @@ func addDependenciesForNativeModules(ctx android.BottomUpMutatorContext,
 		{Mutator: "arch", Variation: arch},
 		{Mutator: "image", Variation: "core"},
 		{Mutator: "link", Variation: "shared"},
+		{Mutator: "version", Variation: ""}, // "" is the non-stub variant
 	}, sharedLibTag, native_shared_libs...)
 
 	ctx.AddFarVariationDependencies([]blueprint.Variation{

apex/apex_test.go

@@ -276,13 +276,21 @@ func TestApexWithStubs(t *testing.T) {
 
 		cc_library {
 			name: "mylib3",
-				srcs: ["mylib.cpp"],
+			srcs: ["mylib.cpp"],
-				system_shared_libs: [],
+			shared_libs: ["mylib4"],
+			system_shared_libs: [],
 			stl: "none",
 			stubs: {
 				versions: ["10", "11", "12"],
 			},
 		}
+
+		cc_library {
+			name: "mylib4",
+			srcs: ["mylib.cpp"],
+			system_shared_libs: [],
+			stl: "none",
+		}
 	`)
 
 	apexRule := ctx.ModuleForTests("myapex", "android_common_myapex").Rule("apexRule")