k: ensure memset gets linked properly.
k: ensure memset gets linked properly.

This works around a bug in GCC 4.8 with LTO enabled, where references
generated by the compiler are found *after* input sections have been
discarded.  The kernel never calls memset directly; all calls are in
constructor invocations.

cbiffle/brittle-kernel,cbiffle/brittle-kernel,cbiffle/brittle-kernel,cbiffle/brittle-kernel