dev-db/mysql++: rev bump to ease migration to dev-db/mysql-connector-c

dev-db/mysql++: rev bump to ease migration to dev-db/mysql-connector-c

Commit 9a7a60296b1685847c0c3c463de532a4245d4c11 replaced
virtual/libmysqlclient dependency with dev-db/mysql-connector-c atom
without a rev bump.

To avoid unecessary user interaction for users not using emerge's
--changed-deps=y because we are already pushing towards removal of
virtual/libmysqlclient (see commit 08b83d736f77fd5dffa9cd5f6b1b44771726ce94),
this commit will now force the re-installation through rev bump
to ease migration.

Package-Manager: Portage-2.3.72, Repoman-2.3.17
Signed-off-by: Thomas Deutschmann <whissi@gentoo.org>