use LLVM linker (#2713)
use LLVM linker (#2713)

* use LLVM linker

* error message improved in case of filenotfound

* linting error fixed

Huyuwei/tvm,Huyuwei/tvm,sxjscience/tvm,dmlc/tvm,sxjscience/tvm,tqchen/tvm,dmlc/tvm,tqchen/tvm,Laurawly/tvm-1,Huyuwei/tvm,dmlc/tvm,tqchen/tvm,sxjscience/tvm,Huyuwei/tvm,tqchen/tvm,sxjscience/tvm,sxjscience/tvm,sxjscience/tvm,Laurawly/tvm-1,Huyuwei/tvm,tqchen/tvm,sxjscience/tvm,Laurawly/tvm-1,dmlc/tvm,tqchen/tvm,dmlc/tvm,Laurawly/tvm-1,dmlc/tvm,tqchen/tvm,Laurawly/tvm-1,tqchen/tvm,dmlc/tvm,Laurawly/tvm-1,Laurawly/tvm-1,sxjscience/tvm,Huyuwei/tvm,Laurawly/tvm-1,Huyuwei/tvm,dmlc/tvm,tqchen/tvm,sxjscience/tvm,Huyuwei/tvm,Huyuwei/tvm,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,tqchen/tvm