another gcc-10 fix for stable kernels

[Thomas Backlund <tmb@xxxxxxxxxx>]

Hi,

this one should be added to -stable trees too:

commit b1112139a103b4b1101d0d2d72931f2d33d8c978
Author: Sergei Trofimovich <slyfox@xxxxxxxxxx>
Date:   Tue Mar 17 00:07:18 2020 +0000

    Makefile: disallow data races on gcc-10 as well

--
Thomas