Add Bazel BUILD file

This enables this project to be built using Bazel (https://bazel.io).

Bug: 31060257
Change-Id: I7067b9c31a855618b7896204745a80ceae15e449
diff --git a/BUILD b/BUILD
new file mode 100644
index 0000000..b4b9028
--- /dev/null
+++ b/BUILD
@@ -0,0 +1,24 @@
+# Bazel (https://bazel.io/) BUILD file for apksig library and apksigner tool.
+
+licenses(["notice"])  # Apache License 2.0
+
+java_library(
+    name = "apksig",
+    srcs = glob([
+        "src/main/java/**/*.java",
+    ]),
+    visibility = ["//visibility:public"],
+)
+
+java_binary(
+    name = "apksigner",
+    srcs = glob([
+        "src/apksigner/java/**/*.java",
+    ]),
+    main_class = "com.android.apksigner.ApkSignerTool",
+    resources = glob([
+        "src/apksigner/java/**/*.txt",
+    ]),
+    visibility = ["//visibility:public"],
+    deps = [":apksig"],
+)