Fix build for JDK 7

The latest update of javac broke JDK 7 because we were using a JavaBuilder
that is not synced with the javac. Fix it by using javac from our 0.1.0
release.

--
MOS_MIGRATED_REVID=104431158
diff --git a/scripts/ci/build.sh b/scripts/ci/build.sh
index c2c774a..aead279 100755
--- a/scripts/ci/build.sh
+++ b/scripts/ci/build.sh
@@ -105,9 +105,12 @@
 function setup_jdk7() {
   # This is a JDK 7 JavaBuilder from release 0.1.0.
   local javabuilder_url="https://storage.googleapis.com/bazel/0.1.0/JavaBuilder_deploy.jar"
+  local javac_url="https://github.com/bazelbuild/bazel/blob/0.1.0/third_party/java/jdk/langtools/javac.jar?raw=true"
   sed -i.bak 's/_version = "8"/_version = "7"/' tools/jdk/BUILD
   rm -f tools/jdk/BUILD.bak
+  rm -f third_party/java/jdk/langtools/javac.jar
   curl -s -o tools/jdk/JavaBuilder_deploy.jar "${javabuilder_url}"
+  curl -s -o third_party/java/jdk/langtools/javac.jar "${javac_url}"
   export BAZEL_ARGS="--singlejar_top=//src/java_tools/singlejar:bootstrap_deploy.jar \
       --genclass_top=//src/java_tools/buildjar:bootstrap_genclass_deploy.jar \
       --ijar_top=//third_party/ijar"