Fix grammar in OS error string.
Fix grammar in OS error string.

kernelsauce/turbo,mniestroj/turbo,luastoned/turbo,YuanPeir-Chen/turbo-support-mipsel,ddysher/turbo,ddysher/turbo,zcsteele/turbo,YuanPeir-Chen/turbo-support-mipsel,luastoned/turbo,zcsteele/turbo