Add recovery image sdk trait to cc_library_headers

Allows an sdk to require that a cc_library_headers module provides a
recovery image variant for the prebuilt.

Previously, "recovery_available: true" would be set in the generated
prebuilt snapshot for any sdk member that specified
"recovery_available: true" in the source module. This change will only
add that setting to the snapshot if the recovery image variant trait
was explicitly requested for a member.

Bug: 195754365
Test: m nothing
Change-Id: I7d79ccdec843127f7852d82b4b163021e30a79a7

cc/library_sdk_member.go

@@ -133,6 +133,16 @@ func (mt *librarySdkMemberType) AddDependencies(ctx android.SdkDependencyContext
 				imageVariations: []blueprint.Variation{{Mutator: "image", Variation: android.CoreVariation}},
 				targets:         targets,
 			})
+
+			// If required add additional dependencies on the image:recovery variants.
+			if ctx.RequiresTrait(lib, recoveryImageRequiredSdkTrait) {
+				memberDependencies = append(memberDependencies, memberDependency{
+					imageVariations: []blueprint.Variation{{Mutator: "image", Variation: android.RecoveryVariation}},
+					// Only add a dependency on the first target as that is the only one which will have an
+					// image:recovery variant.
+					targets: targets[:1],
+				})
+			}
 		}
 
 		// For each dependency in the list add dependencies on the targets with the correct variations.
@@ -189,7 +199,7 @@ func (mt *librarySdkMemberType) AddPrebuiltModule(ctx android.SdkMemberContext,
 		pbm.AddProperty("native_bridge_supported", true)
 	}
 
-	if proptools.Bool(ccModule.Properties.Recovery_available) {
+	if ctx.RequiresTrait(recoveryImageRequiredSdkTrait) {
 		pbm.AddProperty("recovery_available", true)
 	}