Upgrade sleef to v3.4.0. (#26749)
Summary:
This reset the sleef submodule to upstream, since everything else except
a small build sanity fix
<https://github.com/zdevito/sleef/commit/191f655caa25526ae226cf88dd2529265176014a>
has been merged to upstream. The new release includes an important fix
for trigonometric functions on MacOS, which would unblock https://github.com/pytorch/pytorch/issues/26431.
This should supersede https://github.com/pytorch/pytorch/issues/20536.
Close https://github.com/pytorch/pytorch/issues/20536.
cc colesbury resistor
Pull Request resolved: https://github.com/pytorch/pytorch/pull/26749
Differential Revision: D17572783
Pulled By: ezyang
fbshipit-source-id: dd7827e8c8500a0050e3e318d184134c792d3ecc
