filesystems property can be specific to arch

Some filesystems (like boot_image type) are arch-specific. This change
allows us to have filesystems property inside the arch.<arch> struct.

Bug: 178978059
Test: m
Change-Id: I09faa6186b4a3fa35f348fc0805d894b4dc27ffd
diff --git a/apex/apex.go b/apex/apex.go
index cfeac72..e06a967 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -208,6 +208,9 @@
 
 	// List of native tests that are embedded inside this APEX.
 	Tests []string
+
+	// List of filesystem images that are embedded inside this APEX bundle.
+	Filesystems []string
 }
 
 type apexMultilibProperties struct {
@@ -580,6 +583,7 @@
 	ctx.AddFarVariationDependencies(libVariations, jniLibTag, nativeModules.Jni_libs...)
 	ctx.AddFarVariationDependencies(libVariations, sharedLibTag, nativeModules.Native_shared_libs...)
 	ctx.AddFarVariationDependencies(rustLibVariations, sharedLibTag, nativeModules.Rust_dyn_libs...)
+	ctx.AddFarVariationDependencies(target.Variations(), fsTag, nativeModules.Filesystems...)
 }
 
 func (a *apexBundle) combineProperties(ctx android.BottomUpMutatorContext) {