[libcxx] Fix a missed case needing "system header" markings for init_priority(100)

This was missed in D95972 / 7c49052b170f76f19be64a5572d31ad8f5df4e61,
as this codepath isn't exercised by CI yet.

Differential Revision: https://reviews.llvm.org/D111292

NOKEYCHECK=True
GitOrigin-RevId: 1b53413a3848aa6e3250902c37cc0d9862c767b6
diff --git a/src/chrono.cpp b/src/chrono.cpp
index 6f5d2ba..b5dd0ee 100644
--- a/src/chrono.cpp
+++ b/src/chrono.cpp
@@ -80,7 +80,9 @@
   GetSystemTimeAsFileTimePtr fp;
 };
 
+# 83 "chrono.cpp" 1 3
 GetSystemTimeInit GetSystemTimeAsFileTimeFunc _LIBCPP_INIT_PRIORITY_MAX;
+# 85 "chrono.cpp" 2
 } // namespace
 
 #endif