Split Allow_missing_dependencies from Unbundled_build

There are stripped down branches used to build other things than just
unbundled apps (like the AOSP llvm branch used to build llvm prebuilts).

Change-Id: Id772eac8c4622458591b52f9f27723fdb83f9a85
diff --git a/common/variable.go b/common/variable.go
index 04856e1..350bfda 100644
--- a/common/variable.go
+++ b/common/variable.go
@@ -73,9 +73,10 @@
 	CrossHostArch          *string `json:",omitempty"`
 	CrossHostSecondaryArch *string `json:",omitempty"`
 
-	Unbundled_build   *bool `json:",omitempty"`
-	Brillo            *bool `json:",omitempty"`
-	Malloc_not_svelte *bool `json:",omitempty"`
+	Allow_missing_dependencies *bool `json:",omitempty"`
+	Unbundled_build            *bool `json:",omitempty"`
+	Brillo                     *bool `json:",omitempty"`
+	Malloc_not_svelte          *bool `json:",omitempty"`
 }
 
 func boolPtr(v bool) *bool {