Bug#33615013 Fix Doxygen warnings reported by Doxygen v1.9.2

Fix new doxygen warnings reported by Doxygen 1.9.2.

Change-Id: Iaf4096f3eeb7eb9e298d728a97fc715b86104381

Author: marcalff

sql/auth/sql_auth_cache.cc

@@ -699,7 +699,7 @@ void append_auth_id(const THD *thd, ACL_USER *acl_user, String *str) {
 }
 
 /**
-  Append the user@host to the str
+  Append the user\@host to the str.
 
   @param [in]       thd      The THD to find the SQL mode
   @param [in]       user     Username to append to authID

sql/auth/sql_authentication.cc

@@ -4325,7 +4325,7 @@ static int compare_native_password_with_hash(const char *hash,
   The server name is *mysql_native_password*
   </li>
   <li>
-  The client name is *mysql_native_password"
+  The client name is *mysql_native_password*
   </li>
   <li>
   Client side requires an 20-byte random challenge from server
@@ -4347,7 +4347,7 @@ static int compare_native_password_with_hash(const char *hash,
   @ref page_protocol_connection_phase_authentication_methods_old_password_authentication
 
   1. using a tested, crypto-graphic hashing function (SHA1)
-  2. knowning the content of the hash in the mysql.user table isn't enough
+  2. knowing the content of the hash in the mysql.user table isn't enough
      to authenticate against the MySQL Server.
 
   The network packet content for the password is calculated by:

sql/coding_guidelines.h

@@ -137,7 +137,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
   <em>*  **********</em>/</pre>
   </td></tr></table></div>
 
-  - When writing single-line comments, the '/<em>*</em>' and '<em>*</em>/" are
+  - When writing single-line comments, the '/<em>*</em>' and '<em>*</em>/' are
     on the same line. For example:
 
   <div style="margin-left:30px">

sql/item.h

@@ -3846,7 +3846,7 @@ class Item_ident : public Item {
     If column is from an expression, a string generated from that expression.
 
     Notice that a column can be aliased in two ways:
-    1. With an explicit column alias, or <as clause>, or
+    1. With an explicit column alias, or @<as clause@>, or
     2. With only a column name specified, which differs from the table's
        column name due to case insensitivity.
     In both cases field_name will differ from m_orig_field_name.

sql/regexp/errors.cc

@@ -51,7 +51,7 @@ struct UErrorCodeHash {
   Map from ICU error codes to MySQL dittos. We strive to keep this list in the
   same order as the enum UErrorCode in common/unicode/utypes.h.
 
-  ICU version 67 introduced a new implementation for '\X'
+  ICU version 67 introduced a new implementation for '@\X'
   "Match a Grapheme Cluster". This means that our bundled version will
   return ER_REGEXP_MISSING_RESOURCE while for system ICU we return
   ER_WARN_REGEXP_USING_DEFAULT as a Note.