[OpenMP] [AIX] Add missing } in openmp/runtime/src/z_Linux_util.cpp (#133973)

Changes from https://github.com/llvm/llvm-project/pull/133034 removed a
`}` presumably accidentally that are causing failures in the AIX flang
bot.

openmp/runtime/src/z_Linux_util.cpp

@@ -2520,6 +2520,8 @@ int __kmp_get_load_balance(int max) {
   glb_running_threads = running_threads;
 
   return running_threads;
+}
+
 #elif KMP_OS_HAIKU
 
 int __kmp_get_load_balance(int max) { return -1; }