No such file or directory about m_string.h

[Joungkyun]

From mariadb 10.3.24, 10.4.14 or later versions, m_string.h was not found.

[root@host src]# make
... blah blah
In file included from mysql_aes256.c:40:0:
/usr/local/mysql/include/mysql/my_sys.h:3:2: warning: #warning This file should not be included by clients, include only <mysql.h> [-Wcpp]
 #warning This file should not be included by clients, include only <mysql.h>
  ^
mysql_aes256.c:42:47: fatal error: m_string.h: No such file or directory
   #include <m_string.h>  /* To get strmov() */
                                               ^
compilation terminated.
make[2]: *** [lib_mysqludf_aes256_la-mysql_aes256.lo] Error 1
make[2]: Leaving directory `/home/maria/lib_mysqludf_aes256-master/src'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/home/maria/lib_mysqludf_aes256-master/src'
make: *** [all-recursive] Error 1

[Joungkyun]

solved in #9