Also fixes fdo#42899 and fdo#67685 in a different way; the previous fix
for fdo#42899 caused the problem with password-protected libraries for
which the password is not known: only the binary representation of the
BAISC module was stored, not the source code; by simply copying from the
source storage the problem can be avoided.

It would be possible to ask for the password when storing, but that
would not work when non-interactive (called via API).

An alternative fix would be to pass in the
SfxObjectShell::IsSetModifyEnabled() flag and actually reset the BASIC
library's modify flag correctly, but that requires adding a
parameter to XStorageBasedLibraryContainer::storeLibrariesToStorage().

(regression from af34774d )

Change-Id: I4701401f35171139fc2fe8d225d13d4e533091a0