Revert "Revert "mkbootimg: Build mkbootimg with Soong.""

This reverts commit 55a78bf5801f78ccb33ad689cc33cf3d1dcedc3a.

There's no change in this CL from the initial landing. The earlier crash
was caused by manifest setup in build-tools and clang-tools branches,
which has been addressed by the following CLs.
https://android-review.googlesource.com/c/platform/manifest/+/769045
https://android-review.googlesource.com/c/platform/manifest/+/769044

Bug: 116698229
Change-Id: I33701c9f77e814257cc5c65ad7aa587835ae00ad
Test: TreeHugger
diff --git a/mkbootimg/Android.bp b/mkbootimg/Android.bp
index 576a677..c3cf746 100644
--- a/mkbootimg/Android.bp
+++ b/mkbootimg/Android.bp
@@ -31,3 +31,34 @@
     header_libs: ["libmkbootimg_abi_headers"],
     export_header_lib_headers: ["libmkbootimg_abi_headers"],
 }
+
+python_defaults {
+    name: "mkbootimg_defaults",
+
+    version: {
+        py2: {
+            enabled: true,
+            embedded_launcher: true,
+        },
+        py3: {
+            enabled: false,
+            embedded_launcher: false,
+        },
+    },
+}
+
+python_binary_host {
+    name: "mkbootimg",
+    defaults: ["mkbootimg_defaults"],
+    srcs: [
+        "mkbootimg.py",
+    ],
+}
+
+python_binary_host {
+    name: "unpack_bootimg",
+    defaults: ["mkbootimg_defaults"],
+    srcs: [
+        "unpack_bootimg.py",
+    ],
+}