reject kPackInfo with missing pack sizes in readPackInfo

[kali834x]

readPackInfo reads the numPackStreams field but only allocates and fills archive.packSizes inside the optional kSize property block, so a crafted 7z whose kPackInfo declares a non-zero packed stream count and omits kSize leaves packSizes as the default empty array. the sanity pass does not catch it: sanityCheckPackInfo sets numberOfPackedStreams from the declared count whether or not kSize is present, so the count comparison in sanityCheckUnpackInfo still matches. calculateStreamMap then builds a zero-length packStreamOffsets while folderFirstPackStreamIndex[0] stays 0, and the first getNextEntry indexes archive.packSizes[0] in buildDecoderStack and packStreamOffsets[0] in reopenFolderInputStream, throwing ArrayIndexOutOfBoundsException out of getNextEntry which only declares IOException. require packSizes.length to equal the declared count in readPackInfo, mirroring the isEmpty(packSizes) guard the encoded-header path already has; an archive that legitimately declares zero packed streams still passes since 0 == 0.

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