Call SkipInstall before InstallFile

InstallFile skips install only if SkipInstall is called before
InstallFile.

Bug: 190442286
Test: build/soong/scripts/build-ndk-prebuilts.sh
Change-Id: Ic497e34816ea5ac23be45e34c242b59bf1a01e28
diff --git a/build/soong/sepolicy_vers.go b/build/soong/sepolicy_vers.go
index 0d938e7..9d1fe78 100644
--- a/build/soong/sepolicy_vers.go
+++ b/build/soong/sepolicy_vers.go
@@ -82,13 +82,13 @@
 	rule.Command().Text("echo").Text(ver).Text(">").Output(out)
 	rule.Build("sepolicy_vers", v.Name())
 
-	v.installPath = android.PathForModuleInstall(ctx, "etc", "selinux")
-	v.installSource = out
-	ctx.InstallFile(v.installPath, v.stem(), v.installSource)
-
 	if !v.installable() {
 		v.SkipInstall()
 	}
+
+	v.installPath = android.PathForModuleInstall(ctx, "etc", "selinux")
+	v.installSource = out
+	ctx.InstallFile(v.installPath, v.stem(), v.installSource)
 }
 
 func (v *sepolicyVers) AndroidMkEntries() []android.AndroidMkEntries {