A recent zlib build with optimization for ARM exposed an issue in git's
packfile handling.
Thanks to Pavel Cahyna for the initial report and debugging and Jeremy
Linton for further diagnosis and the subsequent patch.
The patch is currently being discussed upstream¹. Until it is accepted,
apply it only on aarch64 to avoid any unexpected issues with other
arches.
¹ https://public-inbox.org/git/20180525231713.23047-1-lintonrjeremy@gmail.com/T/#u
