Add missing cleanup code for cached indirect lock pool.

This change fixes one issue reported at https://llvm.org/bugs/show_bug.cgi?id=26184
There was missing cleanup code for the cached indirect lock pool. The change
will fix the reported case where it tries to initialize a lock after runtime
cleanup/reinitialization, but it is still possible that the user program runs
into another problem because most test programs have a call to __kmpc_set_lock
after cleanup/reinitialization without calling __kmpc_init_lock causing a crash/hang.

llvm-svn: 258528

openmp/runtime/src/kmp_lock.cpp

@@ -3578,6 +3578,7 @@ __kmp_cleanup_indirect_user_locks()
             __kmp_free(ll->lock);
             ll->lock = NULL;
         }
+        __kmp_indirect_lock_pool[k] = NULL;
     }
     // Clean up the remaining undestroyed locks.
     for (i = 0; i < __kmp_i_lock_table.next; i++) {