MFC r303285:

Change bsdiff to use divsufsort suffix sort library instead of qsufsort,
which is more efficient.

Note that for now we do not create a separate library for libdivsufsort
because it's not used anywhere else.

Obtained from: Chromium

Change bsdiff to use divsufsort suffix sort library instead of qsufsort,
which is more efficient.

Note that for now we do not create a separate library for libdivsufsort
because it's not used anywhere else.

Obtained from: Chromium
MFC after: 2 months

Vendor import of libdivsufsort, a software library that implements
a lightweight suffix array construction algorithm.

Obtained from: https://github.com/y-256/libdivsufsort