Build proguard zips in soong-only builds

This builds the zips but doesn't dist them, I'll do that in a followup.

Bug: 395160816
Test: Diffed proguard-dict.zip proguard-usage.zip and proguard-dict-mapping.textproto between soong and make
Change-Id: Ic112427e4a2fdaf92a1d0a96d0f1c100b57be37a
diff --git a/filesystem/filesystem.go b/filesystem/filesystem.go
index 1ce6131..28eb36d 100644
--- a/filesystem/filesystem.go
+++ b/filesystem/filesystem.go
@@ -33,11 +33,14 @@
 	"github.com/google/blueprint/proptools"
 )
 
+var pctx = android.NewPackageContext("android/soong/filesystem")
+
 func init() {
 	registerBuildComponents(android.InitRegistrationContext)
 	registerMutators(android.InitRegistrationContext)
 	pctx.HostBinToolVariable("fileslist", "fileslist")
 	pctx.HostBinToolVariable("fs_config", "fs_config")
+	pctx.HostBinToolVariable("symbols_map", "symbols_map")
 }
 
 func registerBuildComponents(ctx android.RegistrationContext) {
@@ -576,8 +579,6 @@
 	return txt, json
 }
 
-var pctx = android.NewPackageContext("android/soong/filesystem")
-
 func (f *filesystem) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 	validatePartitionType(ctx, f)
 	if f.filesystemBuilder.ShouldUseVintfFragmentModuleOnly() {