Use more recent "dx.jar" than is available through Maven Central

This lets us ditch pre-Java-8 in the Gradle build.  (The official WALA
master branch recently got rid of pre-Java-8 in its Maven build.)
That, in turn, lets two "com.ibm.wala.dalvik.test" tests pass that
previously were failing.  We still have two other failing tests in
that subproject, but this is definitely progress!

Our Gradle build scripts manage the entire process of downloading and
locally installing the appropriate Android SDK.  That includes
automatically accepting a license.  Maybe some lawyer will throw a fit
about that some day.  Until then, I'd rather have a build system that
does everything needed without imposing additional manual steps on
developers.

com.ibm.wala.dalvik.test/build.gradle

@@ -6,20 +6,6 @@ sourceSets.test {
 		]
 }
 
-dependencies {
-	testCompile(
-		'com.google.android.tools:dx:1.7',
-		'junit:junit:4.11',
-		'org.osgi:org.osgi.core:4.2.0',
-		project(':com.ibm.wala.core'),
-		project(':com.ibm.wala.dalvik'),
-		project(':com.ibm.wala.shrike'),
-		project(':com.ibm.wala.util'),
-		project(configuration: 'testArchives', path: ':com.ibm.wala.core.tests'),
-		)
-	testRuntime 'com.google.android:android:4.1.1.4'
-}
-
 task cloneDroidBench(type: Exec) {
 	// TODO: download to somewhere private to this build tree; update code that looks in "/tmp" accordingly
 	def destDir = file('/tmp/DroidBench')
@@ -42,19 +28,55 @@ task verifyAndroidJar(type: VerifyWithStamp, dependsOn: downloadAndroidJar) {
 	checksum '88be04f4d84d58fadee2e780a322fdb9'
 }
 
-task copyDxJar(type: Sync) {
-	from configurations.testCompile.files {
-		include '**/dx-1.7.jar'
-		rename 'dx-1.7.jar', 'dx.jar'
-	}
+task downloadAndroidSdk(type: de.undercouch.gradle.tasks.download.Download) {
+	src 'https://dl.google.com/android/repository/sdk-tools-linux-3859397.zip'
+	dest temporaryDir
+	overwrite false
+}
+
+task verifyAndroidSdk(type: VerifyWithStamp, dependsOn: downloadAndroidSdk) {
+	src files(downloadAndroidSdk)[0]
+	algorithm 'SHA-256'
+	checksum '444e22ce8ca0f67353bda4b85175ed3731cae3ffa695ca18119cbacef1c1bea0'
+}
+
+task unpackAndroidSdk(type: Sync, dependsOn: verifyAndroidSdk) {
+	from zipTree(verifyAndroidSdk.src)
+	into temporaryDir
+}
+
+task installAndroidBuildTools(type: Exec, dependsOn: unpackAndroidSdk) {
+	def manager = "${unpackAndroidSdk.outputs.files[0]}/tools/bin/sdkmanager"
+	commandLine 'sh', '-ceu', "yes | $manager build-tools\\;26.0.2 >/dev/null"
+	inputs.dir "${unpackAndroidSdk.outputs.files[0]}/tools"
+	outputs.dir "${unpackAndroidSdk.outputs.files[0]}/build-tools"
+}
+
+task copyDxJar(type: Sync, dependsOn: installAndroidBuildTools) {
+	from "${unpackAndroidSdk.outputs.files[0]}/build-tools/26.0.2/lib/dx.jar"
 	into 'lib'
 }
 
 clean.dependsOn cleanCopyDxJar
 
+compileTestJava.dependsOn copyDxJar
+
+dependencies {
+	testCompile(
+		'junit:junit:4.11',
+		'org.osgi:org.osgi.core:4.2.0',
+		files("${copyDxJar.outputs.files[0]}/dx.jar"),
+		project(':com.ibm.wala.core'),
+		project(':com.ibm.wala.dalvik'),
+		project(':com.ibm.wala.shrike'),
+		project(':com.ibm.wala.util'),
+		project(configuration: 'testArchives', path: ':com.ibm.wala.core.tests'),
+		)
+	testRuntime 'com.google.android:android:4.1.1.4'
+}
+
 processTestResources {
 	dependsOn cloneDroidBench
-	dependsOn copyDxJar
 
 	dependsOn verifyAndroidJar
 	from downloadAndroidJar
@@ -69,8 +91,6 @@ test {
 	maxHeapSize = '800M'
 
 	// https://github.com/liblit/WALA/issues/5 and possibly https://github.com/wala/WALA/issues/268
-	exclude '**/DalvikAnnotationsTest.class'
 	exclude '**/DynamicDalvikComparisonJavaLibsTest.class'
 	exclude '**/DynamicDalvikComparisonTestForAndroidLibs.class'
-	exclude '**/JVMLDalvikComparisonTest.class'
 }