[clang] [clang][index][USR] Fix build issue introduced in #205430 (PR #205954)

[Ziqing Luo via cfe-commits]

ziqingluo-90 wrote:

To fix the build bot: https://lab.llvm.org/buildbot/#/builders/10/builds/30742

https://github.com/llvm/llvm-project/pull/205954