MDEV-23526 InnoDB leaks memory for some static objects

A leak of the contents of fil_system.ssd that was introduced in
commit 10dd290b (MDEV-17380)
was caught by implementing SAFEMALLOC instrumentation of operator new.
I did not try to find out how to make AddressSanitizer or Valgrind
detect it.

fil_system_t::close(): Clear fil_system.ssd.

The leak was identified and a fix suggested by Michael Widenius
and Vicențiu Ciorbaru.

storage/innobase/fil/fil0fil.cc

@@ -1610,22 +1610,28 @@ void fil_system_t::create(ulint hash_size)
 
 void fil_system_t::close()
 {
-	ut_ad(this == &fil_system);
-	ut_a(!UT_LIST_GET_LEN(LRU));
-	ut_a(unflushed_spaces.empty());
-	ut_a(!UT_LIST_GET_LEN(space_list));
-	ut_ad(!sys_space);
-	ut_ad(!temp_space);
-
-	if (is_initialised()) {
-		m_initialised = false;
-		hash_table_free(spaces);
-		spaces = NULL;
-		mutex_free(&mutex);
-		fil_space_crypt_cleanup();
-	}
+  ut_ad(this == &fil_system);
+  ut_a(!UT_LIST_GET_LEN(LRU));
+  ut_a(unflushed_spaces.empty());
+  ut_a(!UT_LIST_GET_LEN(space_list));
+  ut_ad(!sys_space);
+  ut_ad(!temp_space);
+
+  if (is_initialised())
+  {
+    m_initialised= false;
+    hash_table_free(spaces);
+    spaces = nullptr;
+    mutex_free(&mutex);
+    fil_space_crypt_cleanup();
+  }
+
+  ut_ad(!spaces);
 
-	ut_ad(!spaces);
+#ifdef UNIV_LINUX
+  ssd.clear();
+  ssd.shrink_to_fit();
+#endif /* UNIV_LINUX */
 }
 
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