[NFC][OpenMP] Silent unused variable in `kmp_collapse.cpp`

GitOrigin-RevId: fa9ee4a7f9f7fb9f586d40939269205fc3061c17
diff --git a/runtime/src/kmp_collapse.cpp b/runtime/src/kmp_collapse.cpp
index e63a980..f1bf049 100644
--- a/runtime/src/kmp_collapse.cpp
+++ b/runtime/src/kmp_collapse.cpp
@@ -1482,8 +1482,8 @@
                                     original_bounds_nest[0].ub0_u64);
   kmp_uint64 outer_lb0 = kmp_fix_iv(original_bounds_nest[0].loop_iv_type,
                                     original_bounds_nest[0].lb0_u64);
-  kmp_uint64 inner_ub0 = kmp_fix_iv(original_bounds_nest[1].loop_iv_type,
-                                    original_bounds_nest[1].ub0_u64);
+  [[maybe_unused]] kmp_uint64 inner_ub0 = kmp_fix_iv(
+      original_bounds_nest[1].loop_iv_type, original_bounds_nest[1].ub0_u64);
   // calculate the chunk's lower and upper bounds
   // the total number of iterations in the loop is the sum of the arithmetic
   // progression from the outer lower to outer upper bound (inclusive since the