Enable pro-type-cstyle-cast checks

We actually do a pretty good job of this, and only have one C style
cast, that's part of an openssl macro, so ignore the one, and enable the
checks.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: Ie0462ee947c8310457365ba2aeea78caedb93da1
diff --git a/http/http_connection.hpp b/http/http_connection.hpp
index ad6855f..84f5c18 100644
--- a/http/http_connection.hpp
+++ b/http/http_connection.hpp
@@ -219,8 +219,9 @@
             bool isExKeyUsageClientAuth = false;
             for (int i = 0; i < sk_ASN1_OBJECT_num(extUsage); i++)
             {
-                if (NID_client_auth ==
-                    OBJ_obj2nid(sk_ASN1_OBJECT_value(extUsage, i)))
+                // NOLINTNEXTLINE(cppcoreguidelines-pro-type-cstyle-cast)
+                int nid = OBJ_obj2nid(sk_ASN1_OBJECT_value(extUsage, i));
+                if (NID_client_auth == nid)
                 {
                     isExKeyUsageClientAuth = true;
                     break;