Fixes a custom action in the Office 2010 installer and makes installers
that pack multiple custom actions in an executable faster.

This reverts commit e5917001.
It's not fixing the real issue, filling up buffer while paused is
actually capable of producing quite a few headaches to get it working
right.

The max_lag variable determines how much fuzz is allowed between the
sound cursor and the scheduled times, some filters are inaccurate wrt
time and would skip and overwrite data otherwise.

winmm: The default I/O procedure should return MMIOERR_FILENOTFOUND if the openable file is not found.

This reverts commit ed593fdf.

This reverts commit c94b2687.

Also fixed some comments