* Out of tree build: mysql_install_db to see all .sql files

Since MDEV-7875 (da0991c6), not all sql source files are in the source
directory, maria_add_gis_sp_bootstrap.sql is in the build directory.

This corrects mysql_install_db{.sh} to be aware of the differing
locations.
Signed-off-by: Daniel Black <daniel.black@au.ibm.com>

* Out of tree build: scripts/mysql_install_db.pl.in
Signed-off-by: Daniel Black <daniel.black@au.ibm.com>