revert SET_LLVM flag (#7657)
revert SET_LLVM flag (#7657)

Co-authored-by: Lei Wang <03adec2b109669d35ce24f3888f239b6ce56b13a@users.noreply.github.com>
dmlc/tvm,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,Laurawly/tvm-1,dmlc/tvm,dmlc/tvm,Laurawly/tvm-1,Laurawly/tvm-1,dmlc/tvm,dmlc/tvm,dmlc/tvm,dmlc/tvm,Laurawly/tvm-1,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,Laurawly/tvm-1,Laurawly/tvm-1