Specify the project directory when executing the JDK script

I'm unable to import the project into IntelliJ on a fresh clone on Mac OS without this.

Change-Id: Ib919c126513f40b0111410c5c39adf0f6b801c45
diff --git a/build.gradle b/build.gradle
index 9800595..4699982 100644
--- a/build.gradle
+++ b/build.gradle
@@ -504,7 +504,7 @@
 } else {
     def javaHomeOut = new StringBuilder()
     def javaHomeErr = new StringBuilder()
-    def javaHomeProc = './tools/jdk.py'.execute()
+    def javaHomeProc = './tools/jdk.py'.execute([], projectDir)
     javaHomeProc.waitForProcessOutput(javaHomeOut, javaHomeErr)
     def jdkHome = new File(javaHomeOut.toString().trim())
     if (!jdkHome.exists()) {