Build boot.img with soong

Bug: 377562951
Test: m nothing
Change-Id: Icb0510eb457814fca0cfeece76e8e584a7c17350
diff --git a/fsgen/Android.bp b/fsgen/Android.bp
index 8cd7518..a022581 100644
--- a/fsgen/Android.bp
+++ b/fsgen/Android.bp
@@ -13,6 +13,7 @@
         "soong-kernel",
     ],
     srcs: [
+        "boot_imgs.go",
         "filesystem_creator.go",
         "fsgen_mutators.go",
         "prebuilt_etc_modules_gen.go",