[crac] RFR: Fix missing include file.

[Jan Kratochvil]

It is probably because I am using `--disable-precompiled-headers `.

src/hotspot/share/runtime/threads.cpp: In static member function 'static jint Threads::check_for_restore(JavaVMInitArgs*)': src/hotspot/share/runtime/threads.cpp:415:5: error: 'crac' has not been declared
  415 |     crac::restore();
      |     ^~~~
src/hotspot/share/runtime/threads.cpp: In static member function 'static jint Threads::create_vm(JavaVMInitArgs*, bool*)':
src/hotspot/share/runtime/threads.cpp:494:3: error: 'crac' has not been declared
  494 |   crac::vm_create_start();
      |   ^~~~

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Commit messages:
 - Fix missing include file.

Changes: https://git.openjdk.org/crac/pull/102/files
 Webrev: https://webrevs.openjdk.org/?repo=crac&pr=102&range=00
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/crac/pull/102.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/102/head:pull/102

PR: https://git.openjdk.org/crac/pull/102