Switch X509 ex_* flags to uint32_t.

The public API already expects them to be uint32_t. Fix the internals to
match.

Bug: 516
Change-Id: Ia683cc2fac559ebe0b3c7045e4db551224677c28
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/55706
Auto-Submit: David Benjamin <davidben@google.com>
Commit-Queue: Bob Beck <bbe@google.com>
Reviewed-by: Bob Beck <bbe@google.com>

crypto/x509/internal.h

@@ -151,10 +151,10 @@ struct x509_st {
   // These contain copies of various extension values
   long ex_pathlen;
   long ex_pcpathlen;
-  unsigned long ex_flags;
-  unsigned long ex_kusage;
-  unsigned long ex_xkusage;
-  unsigned long ex_nscert;
+  uint32_t ex_flags;
+  uint32_t ex_kusage;
+  uint32_t ex_xkusage;
+  uint32_t ex_nscert;
   ASN1_OCTET_STRING *skid;
   AUTHORITY_KEYID *akid;
   X509_POLICY_CACHE *policy_cache;