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) {
           ~~~~~~~~^~~
phisiart/tvm,phisiart/tvm,phisiart/tvm,phisiart/tvm,phisiart/tvm,phisiart/tvm,phisiart/tvm