Problem:    Cannot handle binary data.
Solution:   Add the Blob type. (Yasuhiro Matsumoto, closes vim/vim#3638)
https://github.com/vim/vim/commit/6e5ea8d2a995b32bbc5972edc4f827b959f2702f

Nvim-specific Blob conversions are implemented in future commits.

Refactor write_blob() to use a FileDescriptor, as f_writefile() was
refactored to use one (does not apply to read_blob()).

Use var_check_lock() in f_add() for Blobs from v8.1.0897.

Add a modeline to test_blob.vim and fix some doc typos.

Include if_perl.txt's VIM::Blob() documentation. Interestingly, this
function already worked before this port, as it just returns a Blob
string literal, not an actual Blob object.

N/A patches for version.c:

vim-patch:8.1.0741: viminfo with Blob is not tested

Problem:    Viminfo with Blob is not tested.
Solution:   Extend the viminfo test.  Fix reading a blob.  Fixed storing a
            special variable value.
https://github.com/vim/vim/commit/8c8b8bb56c724cc1bfc3d8520eec33f2d399697c

vim-patch:8.1.1022: may use NULL pointer when out of memory

Problem:    May use NULL pointer when out of memory. (Coverity)
Solution:   Check for blob_alloc() returning NULL.
https://github.com/vim/vim/commit/e142a9467a7f6845a426d8db6efedf246d3c13ac

assert() is compiled out for release builds, but we don't want to
continue running in these impossible situations.

This also resolves the "implicit fallthrough" warnings for the asserts
in switch cases.

Problem:    VAR_SPECIAL is also used for booleans.
Solution:   Add VAR_BOOL for better type checking.
https://github.com/vim/vim/commit/9b4a15d5dba354d2e1e02871470bad103f34769a

Problem:    Floating point exception with "%= 0" and "/= 0".
Solution:   Avoid dividing by zero. (Dominique Pelle, closes vim/vim#4058)
https://github.com/vim/vim/commit/e21c1580b7acb598a6e3c38565434fe5d0e2ad7a

Problem:    Incomplete set of assignment operators.
Solution:   Add /=, *= and %=. (Ozaki Kiichi, closes vim/vim#3931)
https://github.com/vim/vim/commit/ff697e6cef8ced7717a21fd525ab3200b2f1724f

After merging +num64, the 64-bit sanitizer builds show that Vim doesn't
buffer the user from C's UB in signed arithmetic.  Upstream doesn't
appear to be [interested] in fixing the issue, so suppress UBSAN until
someone decides to fix the problem.

N.B., the problem existed before but went unnoticed since the sanitizer
builds weren't being run in 32-bit mode.

[interested]: https://groups.google.com/d/topic/vim_dev/_tqf8eQy5eA/discussion