llsm update warns of unused vars
the recent llvm update on macOS produces these warnings
{{{ gary@Pro23 sys_llvm % makeit ../dynamics.cpp:2323:11: warning: variable 'nTimeVary' set but not used [-Wunused-but-set-variable] long int nTimeVary = 0; ^ 1 warning generated. ../grains.cpp:3668:8: warning: variable 'Zg' set but not used [-Wunused-but-set-variable] long Zg = gv.bin[nd].chrg(nz).DustZ; ^ 1 warning generated. ../rt_escprob.cpp:868:16: warning: variable 'i' set but not used [-Wunused-but-set-variable] static int i; ^ 1 warning generated. }}}