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/.clang-tidy b/.clang-tidy
index 462c5bf..93db922 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -207,6 +207,7 @@
 cppcoreguidelines-pro-bounds-array-to-pointer-decay,
 cppcoreguidelines-pro-bounds-pointer-arithmetic,
 cppcoreguidelines-pro-type-const-cast,
+cppcoreguidelines-pro-type-cstyle-cast,
 cppcoreguidelines-pro-type-member-init,
 cppcoreguidelines-pro-type-reinterpret-cast,
 cppcoreguidelines-special-member-functions,
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;