Compiler warnings like one listed below are generated during server build on MacOS:
In file included from server-10.2-MDEV-23564/mysys_ssl/openssl.c:33:
In file included from /usr/local/include/openssl/evp.h:16:
In file included from /usr/local/include/openssl/bio.h:20:
/usr/local/include/openssl/crypto.h:206:10: warning: 'CRYPTO_cleanup_all_ex_data' macro redefined [-Wmacro-redefined]
           ^
  /mariadb/server-10.2-MDEV-23564/include/ssl_compat.h:46:9: note: previous definition is here
          ^

In case MariaDB serer is build with -DCMAKE_BUILD_TYPE=Debug it results in
build error.

The reason of compiler warnings is that header file <ssl_compat.h>
included before the openssl system header files. File ssl_compat.h
contains some macros with the same names as SSL API functions declared
in the openssl system header files. It resulted in duplicate
symbols that produces compiler warnings.

To fix the issue the header file ssl_compat.h should be included
after a line where openssl system header is included.