Bazel: Allow plugins to non-transitively depend on prolog rules

Some plugins, most notably owners-plugin, depend on prolog:common rule.
Given that this rule transitively depends on gerrit-server:server rule,
and this rule depends on virtually whole gerrit build graph, the final
plugin artifact contains effectively the whole gerrit war file content.

To fix that we expose prolog:common in plugin API. Moreover, adjust
prolog_cafe_library to not transitively depend on prolog runtime
library. We can do it, because gerrit-server already depends on it, so
that it's included in gerrit war anyway.

This change allows the owners-plugin to de-duplicate its size from 45 MB
to 1.5 MB only.

Change-Id: I8d7198a911c2da444c1822509988eda7d369af77

gerrit-plugin-api/BUILD

@@ -19,6 +19,7 @@ EXPORTS = [
     "//gerrit-extension-api:api",
     "//gerrit-gwtexpui:server",
     "//gerrit-reviewdb:server",
+    "//gerrit-server/src/main/prolog:common",
     "//lib/commons:lang",
     "//lib/commons:lang3",
     "//lib/dropwizard:dropwizard-core",

lib/prolog/BUILD

@@ -5,6 +5,13 @@ java_library(
     exports = ["@prolog_runtime//jar"],
 )
 
+java_library(
+    name = "runtime-neverlink",
+    data = ["//lib:LICENSE-prologcafe"],
+    visibility = ["//visibility:public"],
+    exports = ["@prolog_runtime//jar:neverlink"],
+)
+
 java_library(
     name = "compiler",
     data = ["//lib:LICENSE-prologcafe"],

lib/prolog/prolog.bzl

@@ -31,6 +31,6 @@ def prolog_cafe_library(
   native.java_library(
     name = name,
     srcs = [':' + name + '__pl2j'],
-    deps = ['//lib/prolog:runtime'] + deps,
+    deps = ['//lib/prolog:runtime-neverlink'] + deps,
     **kwargs
   )