databases/mariadb100-{client,server}: Update to 10.0.23

• Update to 10.0.23
• Re-patch files due to path change in WRKSRC
• Harmonize CONFLICTS and quench portlint warnings
• Use variables to construct INSTALL_CONFLICTS
• Fix json.cpp clang compilation issue
• Refactor and upstream jemalloc patch

Changes:

• https://mariadb.com/kb/en/mariadb/mariadb-10023-changelog/

Reviewed by: koobs (mentor), feld (mentor)
Approved by: koobs (mentor)
Differential Revision: https://reviews.freebsd.org/D4709