* src/lens.c (lns_check_rec): allow 'let rec' with regular RHS
* src/lens.c (lns_check_rec): allow 'let rec' with regular RHS

If the user writes 'let rec l = rhs' and the RHS does not mention l, just
mark the lens as regular and carry on.

pevalme/augeas,MikaelSmith/augeas,kumy/augeas,mlichvar/augeas,kunkku/augeas,dafugg/augeas,dafugg/augeas,raphink/augeas,pevalme/augeas,lutter/augeas,mlichvar/augeas,hercules-team/augeas,jtopjian/augeas,kunkku/augeas,jasperla/augeas,hercules-team/augeas-do-not-use,GeoffWilliams/augeas,MikaelSmith/augeas,mchf/augeas,kumy/augeas,kunkku/augeas,jjlin/augeas,kumy/augeas,kumy/augeas,hercules-team/augeas,mlichvar/augeas,manandbytes/augeas,mchf/augeas,lutter/augeas,jjlin/augeas,jjlin/augeas,GeoffWilliams/augeas,hercules-team/augeas-do-not-use,domcleal/augeas,dafugg/augeas,jasperla/augeas,hercules-team/augeas-do-not-use,pevalme/augeas,lutter/augeas,manandbytes/augeas,domcleal/augeas,domcleal/augeas,raphink/augeas,ptoscano/augeas,ptoscano/augeas,jtopjian/augeas,ptoscano/augeas