Enable pro-type-static-cast-downcast checks

We only had one usage, and it was really bad and breaking const
correctness, so fix it to read the crashdump in inline.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I234946fe09d73a9fa0191a15a89d0b2c26f32337
diff --git a/.clang-tidy b/.clang-tidy
index c15af94..7f36b77 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -211,6 +211,7 @@
 cppcoreguidelines-pro-type-cstyle-cast,
 cppcoreguidelines-pro-type-member-init,
 cppcoreguidelines-pro-type-reinterpret-cast,
+cppcoreguidelines-pro-type-static-cast-downcast,
 cppcoreguidelines-pro-type-vararg,
 cppcoreguidelines-special-member-functions,
 misc-misplaced-const,