Merge branch 'mc/clean-smudge-with-llp64'

The clean/smudge conversion code path has been prepared to better work on platforms where ulong is narrower than size_t. * mc/clean-smudge-with-llp64: clean/smudge: allow clean filters to process extremely large files odb: guard against data loss checking out a huge file git-compat-util: introduce more size_t helpers odb: teach read_blob_entry to use size_t t1051: introduce a smudge filter test for extremely large files test-lib: add prerequisite for 64-bit platforms test-tool genzeros: generate large amounts of data more efficiently test-genzeros: allow more than 2G zeros in Windows