bp2build: mark crt_beginso1 as bp2build_available.

This leaf module is selected as the first cc_object module to be converted by
the bp2build converter.

Test: GENERATE_BAZEL_FILES=true m nothing && bp2build-sync write && bazel build //bionic/libc:crt_beginso1
Change-Id: Idf752e7b5251161a4fbd58ba52b52dd85c8fc92b
diff --git a/libc/Android.bp b/libc/Android.bp
index 6a3a7c0..9427960 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -2078,6 +2078,7 @@
     srcs: ["arch-common/bionic/crtbegin_so.c"],
 
     defaults: ["crt_so_defaults"],
+    bazel_module: { bp2build_available: true },
 }
 
 cc_object {