This is required to fix the build of cl-prevalence with cl-usocket-0.8.8.
* gnu/packages/patches/sbcl-s-sysdeps-bt2.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/lisp-xyz.scm (sbcl-s-sysdeps)[source]: Use it.
Change-Id: I6addc042e16f71b55a2125c1f8eb313023ada411