[DynInst_API:] [dyninst/dyninst] 5025a5: Remove Singleton.h

[Tim Haines <noreply@xxxxxxxxxx>]

  Branch: refs/heads/thaines/remove_Singleton
  Home:   https://github.com/dyninst/dyninst
  Commit: 5025a53105bd328e7448b78e8f781ad126744218
      https://github.com/dyninst/dyninst/commit/5025a53105bd328e7448b78e8f781ad126744218
  Author: Tim Haines <thaines.astro@xxxxxxxxx>
  Date:   2023-10-26 (Thu, 26 Oct 2023)

  Changed paths:
    M common/CMakeLists.txt
    R common/src/Singleton.h
    M instructionAPI/src/Operation.C
    M instructionAPI/src/Register.C
    M instructionAPI/src/Ternary.C

  Log Message:
  -----------
  Remove Singleton.h

It's not used anymore.