Skip version mutator for host/ramdisk/recovery

"version" mutator creates stubs variants for "cc" libraries with
"stubs.versions". These stubs are for APEX-APEX or APEX-Platform
boundaries.

For host/ramdisk/recovery variants, stubs are not necessary.

Exempt-From-Owner-Approval: cp from internal

Bug: 153698496
Test: m
Merged-In: Id576c4318d9d69246a4a7e2fb4145d5fd2ab9416
Change-Id: Id576c4318d9d69246a4a7e2fb4145d5fd2ab9416
(cherry picked from commit c40b5193fefc962d296d587a546d0427d5a77f70)
diff --git a/cc/linkable.go b/cc/linkable.go
index fbe61a4..4a70d48 100644
--- a/cc/linkable.go
+++ b/cc/linkable.go
@@ -39,6 +39,8 @@
 	Shared() bool
 	Toc() android.OptionalPath
 
+	Host() bool
+
 	InRamdisk() bool
 	OnlyInRamdisk() bool