LP:978146 - my.ini with PBXT=OFF has to be placed in DATADIR to be effective

According to the documentation on
http://dev.mysql.com/doc/refman/5.5/en/option-files.html
Windows versions of MySQL/MariaDB searches for:

On Windows, MySQL programs read startup options from the following files, in the specified order (top items are used first).
File Name Purpose
WINDIR\my.ini, WINDIR\my.cnf Global options
C:\my.ini, C:\my.cnf Global options
INSTALLDIR\my.ini, INSTALLDIR\my.cnf Global options

Instead, only when my.ini is placed in DATADIR, the PBXT engine is really OFF, and no more PBXT files are created.

Testcase:
=========
Windows XP 32 bit
INSTALLDIR = C:\MariaDB
DATADIR = C:\MariaDB\data

Place my.ini with the following lines in MariaDB INSTALLDIR:
— BEGIN —
[mysqld]
pbxt=OFF
skip-innodb
skip-name-resolve
— END —

The line 'skip-innodb' can be replaced with 'innodb=OFF', the result is the same.

Start the server.

Expected behavior would be:
120410 16:04:45 [Note] Plugin 'PBXT' is disabled.
120410 16:04:45 [Note] Plugin 'InnoDB' is disabled.
120410 16:04:45 [Note] Plugin 'FEEDBACK' is disabled.

But instead, InnoDB/PBXT database and log files are created:
120410 16:01:49 [Note] PrimeBase XT (PBXT) Engine 1.0.11-7 Pre-GA loaded...
120410 16:01:49 [Note] Paul McCullagh, PrimeBase Technologies GmbH, http://www.primebase.org
InnoDB: The InnoDB memory heap is disabled
InnoDB: Mutexes and rw_locks use Windows interlocked functions
InnoDB: Compressed tables use zlib 1.2.3
120410 16:01:49 InnoDB: Initializing buffer pool, size = 128.0M
120410 16:01:49 InnoDB: Completed initialization of buffer pool
InnoDB: The first specified data file .\ibdata1 did not exist:
InnoDB: a new database to be created!
120410 16:01:49 InnoDB: Setting file .\ibdata1 size to 10 MB
InnoDB: Database physically writes the file full: wait...
120410 16:01:49 InnoDB: Log file .\ib_logfile0 did not exist: new to be created
InnoDB: Setting log file .\ib_logfile0 size to 5 MB
InnoDB: Database physically writes the file full: wait...
120410 16:01:50 InnoDB: Log file .\ib_logfile1 did not exist: new to be created
InnoDB: Setting log file .\ib_logfile1 size to 5 MB
InnoDB: Database physically writes the file full: wait...
InnoDB: Doublewrite buffer not found: creating new
InnoDB: Doublewrite buffer created
InnoDB: Creating foreign key constraint system tables
InnoDB: Foreign key constraint system tables created

Stop server.

Copy my.ini from INSTALLDIR to DATADIR.
Delete created ib_logfile0, ib_logfile1, ibdata1, pbxt-lock in DATADIR.

Restart server.

No more ib* and pbxt* files are created.

Checked this behavior on 5.2.12 and 5.3.6. Couldn't check on 5.5.22 due to https://mariadb.atlassian.net/browse/MDEV-208