Migrate check_elf_file.py to python3

Also, create a python_binary_host so that it runs using the hermetic
python toolchain.

Test: m check-elf-files
Bug: 203436762
Change-Id: I964342a27f6b6c9dcdbbe910d4dc6c9ec00c2213
diff --git a/tools/Android.bp b/tools/Android.bp
index f401058..1f0d406 100644
--- a/tools/Android.bp
+++ b/tools/Android.bp
@@ -59,3 +59,8 @@
   name: "check_radio_versions",
   srcs: ["check_radio_versions.py"],
 }
+
+python_binary_host {
+  name: "check_elf_file",
+  srcs: ["check_elf_file.py"],
+}