Enable windows target

`//tools/apksig` depends on this both directly and transitively, and all
targets must have windows enabled.

Bug: 319296492
Test: TH
Change-Id: Ia290c0a0485f811e282c0d7d205dab73d6f68bdf

credentials/Android.bp

diff --git a/credentials/Android.bp b/credentials/Android.bp
index 2618742..8e744f3 100644
--- a/credentials/Android.bp
+++ b/credentials/Android.bp
@@ -3,6 +3,12 @@
     srcs: [
         "java/**/*.java",
     ],
+    visibility: [
+        "//external/google-auth-library-java:__subpackages__",
+        "//external/grpc-grpc-java:__subpackages__",
+        "//external/sdk-platform-java:__subpackages__",
+        "//tools/apksig",
+    ],
     target: {
         windows: {
             enabled: true,

oauth2_http/Android.bp

diff --git a/oauth2_http/Android.bp b/oauth2_http/Android.bp
index 551effd..5227e19 100644
--- a/oauth2_http/Android.bp
+++ b/oauth2_http/Android.bp
@@ -11,4 +11,15 @@
         "guava",
     ],
     plugins: ["auto_value_plugin"],
+    visibility: [
+        "//external/google-auth-library-java:__subpackages__",
+        "//external/grpc-grpc-java:__subpackages__",
+        "//external/sdk-platform-java:__subpackages__",
+        "//tools/apksig",
+    ],
+    target: {
+        windows: {
+            enabled: true,
+        },
+    },
 }