message: [language] Make useage of fresh stdlib in ir-testuite configurable
  Configurable via the environment variable MOVE_NO_USE_STAGED
  Closes:
  Approved by: runtian-zhou
diff: @@ -14,7 +14,7 @@ use ir_to_bytecode::{
  use libra_types::account_address::AccountAddress;
  use move_ir_types::ast;
  use std::path::Path;
  -use stdlib::{stdlib_modules, StdLibOptions};
  +use stdlib::{env_stdlib_modules, stdlib_modules, use_staged, StdLibOptions};
  struct IRCompiler {
  deps: Vec<VerifiedModule>,
  @@ -52,11 +52,16 @@ impl Compiler for IRCompiler {
  })
  }
  - // Use the default genesis
  + // Use the staged genesis/stdlib unless the the
  + // MOVE_NO_USE_STAGED environment variable is set.
  fn stdlib() -> Option<Vec<VerifiedModule>> {
  + if !use_staged() {
  + Some(env_stdlib_modules().to_vec())
  + } else {
  None
  }
  }
  +}
  fn run_test(path: &Path) -> datatest_stable::Result<()> {
  // The IR tests always run with the staged stdlib
  