soong_config: Add new flag for vendor_init

[FP2: move appropriate parts to /build/soong]
Change-Id: I383f1de230ecf7b79d78fe701b140bd1bc6795f2
diff --git a/android/variable.go b/android/variable.go
index e643c0e..ffd2057 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -124,6 +124,10 @@
 			Static_libs  []string
 			Srcs         []string
 		}
+
+		Target_init_vendor_lib struct {
+			Whole_static_libs []string
+		}
 	} `android:"arch_variant"`
 }
 
@@ -287,6 +291,8 @@
 	ProductHiddenAPIStubsTest   []string `json:",omitempty"`
 
 	TargetFSConfigGen []string `json:",omitempty"`
+
+	Target_init_vendor_lib  *string `json:",omitempty"`
 }
 
 func boolPtr(v bool) *bool {