Add `load()` statements for the builtin java rules & symbols

Loads are being added in preparation for moving the rules/symbols out of
Bazel.

This is the same as Gerrit core change
Ie75bb25d13c453ff290e8bb11fe6acf3b91c9580.

Release-Notes: skip
Change-Id: I00295881eaf43e2b55208cbd4ac24bfab05e6333
diff --git a/tools/classpath.bzl b/tools/classpath.bzl
index d9d7f8e..ea142a8 100644
--- a/tools/classpath.bzl
+++ b/tools/classpath.bzl
@@ -1,3 +1,5 @@
+load("@rules_java//java:defs.bzl", "JavaInfo")
+
 def _classpath_collector(ctx):
     all = []
     for d in ctx.attr.deps:
diff --git a/tools/javadoc.bzl b/tools/javadoc.bzl
index a95989d..5b19bb9 100644
--- a/tools/javadoc.bzl
+++ b/tools/javadoc.bzl
@@ -14,6 +14,8 @@
 
 # Javadoc rule.
 
+load("@rules_java//java:defs.bzl", "JavaInfo", "java_common")
+
 def _impl(ctx):
     zip_output = ctx.outputs.zip
 
diff --git a/tools/pkg_war.bzl b/tools/pkg_war.bzl
index eb6c843..eaffc9b 100644
--- a/tools/pkg_war.bzl
+++ b/tools/pkg_war.bzl
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 # War packaging.
+load("@rules_java//java:defs.bzl", "JavaInfo")
 
 def _add_context(in_file, output):
     input_path = in_file.path