[mod_authn_dbi,mod_authn_mysql] fix coverity issue

src/mod_authn_dbi.c

@@ -336,7 +336,7 @@ mod_authn_crypt_cmp (const char *reqpw, const char *userpw, unsigned long userpw
     char *crypted = crypt(reqpw, userpw);
     size_t crypwlen = (NULL != crypted) ? strlen(crypted) : 0;
     int rc = (crypwlen == userpwlen) ? memcmp(crypted, userpw, crypwlen) : -1;
-    safe_memclear(crypted, crypwlen);
+    if (crypwlen) safe_memclear(crypted, crypwlen);
     return rc;
 
  #else
@@ -456,7 +456,7 @@ mod_authn_dbi_query_build (buffer * const sqlquery, dbi_config * const dbconf, h
                     v = "SHA-256";
                 else if (ai->dalgo & HTTP_AUTH_DIGEST_MD5)
                     v = "MD5";
-                else if (ai->dalgo & HTTP_AUTH_DIGEST_NONE)
+                else if (ai->dalgo == HTTP_AUTH_DIGEST_NONE)
                     v = "NONE";
                 else
                     return NULL;

src/mod_authn_mysql.c

@@ -300,7 +300,7 @@ static int mod_authn_mysql_password_cmp(const char *userpw, unsigned long userpw
         char *crypted = crypt(reqpw, userpw);
         size_t crypwlen = (NULL != crypted) ? strlen(crypted) : 0;
         int rc = (crypwlen == userpwlen) ? memcmp(crypted, userpw, crypwlen) : -1;
-        safe_memclear(crypted, crypwlen);
+        if (crypwlen) safe_memclear(crypted, crypwlen);
         return rc;
     }
     else