Update to Gradle 3.2.

- Add gradle-3.2.bin.zip and gradle-api-3.2.jar (gradle-api-3.2.jar is
  generated using the gradleApi() method).

Change-Id: I3f835e742e4dec7d7a555ad0134ce0efc2e598ed
Test: cd tools && ./gradlew test
diff --git a/PREBUILT b/PREBUILT
index 7c45223..000c68d 100644
--- a/PREBUILT
+++ b/PREBUILT
@@ -15,4 +15,4 @@
 https://services.gradle.org/distributions/gradle-2.14-bin.zip
 https://services.gradle.org/distributions/gradle-2.14.1-bin.zip
 https://services.gradle.org/distributions/gradle-3.0-all.zip
-https://services.gradle.org/distributions/gradle-3.1-bin.zip
+https://services.gradle.org/distributions/gradle-3.2-bin.zip
diff --git a/gradle-3.1-bin.zip b/gradle-3.1-bin.zip
deleted file mode 100644
index f4b73af..0000000
--- a/gradle-3.1-bin.zip
+++ /dev/null
Binary files differ
diff --git a/gradle-3.2-bin.zip b/gradle-3.2-bin.zip
new file mode 100644
index 0000000..0ffb0cb
--- /dev/null
+++ b/gradle-3.2-bin.zip
Binary files differ
diff --git a/gradle-api-3.2.jar b/gradle-api-3.2.jar
new file mode 100644
index 0000000..89d4361
--- /dev/null
+++ b/gradle-api-3.2.jar
Binary files differ