fdo#84686 prevent std::bad_alloc exception by stricter input check

The bugdoc has invalid length (rh.recLen) in header of blipStore's
OfficeArtFBSE record. Therefore LibreOffice read junk for the next
BLIP, and tried to seek to an invalid stream position, which caused
bad allocation exception on 32-bit systems.

Change-Id: I72fae4c2b00216b57736f4409a32c62a40f25785
unused function Calc_nBLIPPos

Change-Id: Iaa4073e2f1c0ccea7a5d63d24e34ac5647a0e7b0