Update inject_virtual_thread.cc (#806)
Update inject_virtual_thread.cc (#806)

This compilation warning is fixed.
src/pass/inject_virtual_thread.cc:43:19: warning: ‘rw_mask’ may be used uninitialized in this function [-Wmaybe-uninitialized]
       if (rw_mask & 2) {
           ~~~~~~~~^~~
tqchen/tvm,dmlc/tvm,dmlc/tvm,Huyuwei/tvm,Huyuwei/tvm,dmlc/tvm,tqchen/tvm,dmlc/tvm,tqchen/tvm,Laurawly/tvm-1,sxjscience/tvm,sxjscience/tvm,Laurawly/tvm-1,Laurawly/tvm-1,sxjscience/tvm,Huyuwei/tvm,sxjscience/tvm,sxjscience/tvm,tqchen/tvm,Huyuwei/tvm,Huyuwei/tvm,Laurawly/tvm-1,sxjscience/tvm,Huyuwei/tvm,Huyuwei/tvm,Laurawly/tvm-1,tqchen/tvm,sxjscience/tvm,sxjscience/tvm,Laurawly/tvm-1,tqchen/tvm,Laurawly/tvm-1,dmlc/tvm,tqchen/tvm,dmlc/tvm,tqchen/tvm,dmlc/tvm,Huyuwei/tvm,dmlc/tvm,dmlc/tvm,Laurawly/tvm-1,sxjscience/tvm,Laurawly/tvm-1,tqchen/tvm,Huyuwei/tvm,Laurawly/tvm-1,tqchen/tvm