Change to -Xshare:auto for 32-bit platforms

The following #ifdef block should be removed. The comments in there is no longer correct.

After JDK-8074345, bytecode rewriting is enabled for non-shared classes. So CDS should no longer affect the performance of benchmarks executed by C2.

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void Arguments::set_ergonomics_flags() {
  select_gc();

#if defined(COMPILER2) || INCLUDE_JVMCI
  // Shared spaces work fine with other GCs but causes bytecode rewriting
  // to be disabled, which hurts interpreter performance and decreases
  // server performance. When -server is specified, keep the default off
  // unless it is asked for. Future work: either add bytecode rewriting
  // at link time, or rewrite bytecodes in non-shared methods.
  if (!DumpSharedSpaces && !RequireSharedSpaces &&
      (FLAG_IS_DEFAULT(UseSharedSpaces) || !UseSharedSpaces)) {
    no_shared_spaces("COMPILER2 default: -Xshare:auto | off, have to manually setup to on.");
  }
#endif
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