Avb sign boot images

The bootimg module had a very different implementation of avb signing
than what was in make. Add an alternate implemenation that is used
when avb_private_key is not set.

Bug: 377562951
Test: m nothing --no-skip-soong-tests
Change-Id: I253bcc8135f3d294eb6e09f39429c84c7c0fc037
diff --git a/android/variable.go b/android/variable.go
index 7ae9a43..e666530 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -610,6 +610,8 @@
 	ProductUseDynamicPartitionSize bool   `json:",omitempty"`
 	CopyImagesForTargetFilesZip    bool   `json:",omitempty"`
 
+	VendorSecurityPatch string `json:",omitempty"`
+
 	// Boot image stuff
 	BuildingRamdiskImage            bool   `json:",omitempty"`
 	ProductBuildBootImage           bool   `json:",omitempty"`
@@ -623,6 +625,8 @@
 	BoardBootHeaderVersion          string `json:",omitempty"`
 	TargetKernelPath                string `json:",omitempty"`
 	BoardUsesGenericKernelImage     bool   `json:",omitempty"`
+	BootSecurityPatch               string `json:",omitempty"`
+	InitBootSecurityPatch           string `json:",omitempty"`
 
 	// Avb (android verified boot) stuff
 	BoardAvbEnable          bool                                `json:",omitempty"`