RISC-V strlen patch

I've got a family commitment that is going to keep me busy more most of 
this evening.  I have an updated strlen patch based on the discussion 
with Adhemerval, Peter B, etc. However, I need to review the test log, 
benchmark log and actually produce the patch per glibc's procedures.

Point being that the strlen adjustment wont hit the lists until late 
tonight.  Not sure if it'll still be considered for the upcoming 
release, but I hope so.

Thanks for your understanding.
Jeff