Fixing dependencies of //external package

We need to query `kind('source file', deps(//external:*))` for sparse checkout, but were block by two issues:

* `//external:remotejdk11_linux` depends on `tools/jdk/jdk.BUILD`, but it was not exported. Although this is not a problem for build, queries like `kind('source file', deps(//external:remotejdk11_linux))` would fail.
* `//external:android_sdk_for_testing` is an alias for `//:dummy`, which is not available in other repositories. This also caused #8175.

This pull request fixed both, including #8175.

Closes #15134.

PiperOrigin-RevId: 438605051

src/main/java/com/google/devtools/build/lib/bazel/rules/android/android.WORKSPACE

@@ -20,12 +20,12 @@ bind(
 
 bind(
     name = "android_sdk_for_testing",
-    actual = "//:dummy",
+    actual = "@bazel_tools//tools/android:empty",
 )
 
 bind(
     name = "android_ndk_for_testing",
-    actual = "//:dummy",
+    actual = "@bazel_tools//tools/android:empty",
 )
 
 bind(

src/test/py/bazel/query_test.py

@@ -38,6 +38,11 @@ def testSimpleQuery(self):
     self._AssertQueryOutput('deps(//foo:top-rule, 1)', '//foo:top-rule',
                             '//foo:dep-rule')
 
+  def testQueryFilesUsedByRepositoryRules(self):
+    self.ScratchFile('WORKSPACE')
+    self._AssertQueryOutputContains("kind('source file', deps(//external:*))",
+                                    '@bazel_tools//tools/jdk:jdk.BUILD')
+
   def testBuildFilesForExternalRepos_Simple(self):
     self.ScratchFile('WORKSPACE', [
         'load("//:deps.bzl", "repos")',

tools/android/BUILD.tools

@@ -417,7 +417,7 @@ alias(
 )
 
 # This is the default value of databinding_annotation_processor if the user does
-# not provide one.
+# not provide one. Also used by the bind rules in android.WORKSPACE.
 filegroup(name = "empty")
 
 alias(

tools/jdk/BUILD.tools

@@ -214,7 +214,10 @@ alias(
     }),
 )
 
-exports_files(["BUILD.java_tools"])
+exports_files([
+    "BUILD.java_tools",
+    "jdk.BUILD",
+])
 
 alias(
     name = "genclass",