Use prebuilts for more tools in unbundled builds

Move the logic from Make that uses prebuilts for more tools for
unbundled builds, and export the values back to make.

Test: m checkbuild
Change-Id: I8c7031e0feaa9328a2b73db6dc8e63e12d1d12f7
diff --git a/java/app_builder.go b/java/app_builder.go
index 348c8b4..ec2f6da 100644
--- a/java/app_builder.go
+++ b/java/app_builder.go
@@ -31,31 +31,13 @@
 var (
 	Signapk = pctx.AndroidStaticRule("signapk",
 		blueprint.RuleParams{
-			Command: `${config.JavaCmd} ${config.JavaVmFlags} -Djava.library.path=$$(dirname $signapkJniLibrary) ` +
-				`-jar $signapkCmd $flags $certificates $in $out`,
-			CommandDeps: []string{"$signapkCmd", "$signapkJniLibrary"},
+			Command: `${config.JavaCmd} ${config.JavaVmFlags} -Djava.library.path=$$(dirname ${config.SignapkJniLibrary}) ` +
+				`-jar ${config.SignapkCmd} $flags $certificates $in $out`,
+			CommandDeps: []string{"${config.SignapkCmd}", "${config.SignapkJniLibrary}"},
 		},
 		"flags", "certificates")
-
-	androidManifestMerger = pctx.AndroidStaticRule("androidManifestMerger",
-		blueprint.RuleParams{
-			Command: "java -classpath $androidManifestMergerCmd com.android.manifmerger.Main merge " +
-				"--main $in --libs $libsManifests --out $out",
-			CommandDeps: []string{"$androidManifestMergerCmd"},
-			Description: "merge manifest files",
-		},
-		"libsManifests")
 )
 
-func init() {
-	pctx.SourcePathVariable("androidManifestMergerCmd", "prebuilts/devtools/tools/lib/manifest-merger.jar")
-	pctx.HostBinToolVariable("aaptCmd", "aapt")
-	pctx.HostJavaToolVariable("signapkCmd", "signapk.jar")
-	// TODO(ccross): this should come from the signapk dependencies, but we don't have any way
-	// to express host JNI dependencies yet.
-	pctx.HostJNIToolVariable("signapkJniLibrary", "libconscrypt_openjdk_jni")
-}
-
 var combineApk = pctx.AndroidStaticRule("combineApk",
 	blueprint.RuleParams{
 		Command:     `${config.MergeZipsCmd} $out $in`,