Hi,

musl 1.1.17 fails to build [1] on arm versions <5 because
of an unsupported clz instruction.
The attached patch by Adrian Bunk [2] fixes this issue.

Kind regards,
  Reiner

[1] https://buildd.debian.org/status/fetch.php?pkg=musl&arch=armel&ver=1.1.17-1&stamp=1508450839
[2] https://bugs.debian.org/879190