bug@35573783 innodb.set_concurrency_in_readonly is failing in trunk

In case of a failed tablespace import, a dangling fil_space
reference count might remain.
The discrepancy could only be noticed in debug builds, using innodb_fast_shutdown=0 .

[ERROR] [MY-011825] [InnoDB] Space id=1319 reference count is 1, while references count found in buffer pool is 0.  fast_shutdown is 0

A solution is to cleanup the reference in fil_tablespace_iterate before we deallocate the block
which didn't happen before, in the case of encountring an error during import.

Change-Id: I63ef19f962e8166df059725b4c2d07a5729d1647

Author: GBuella

storage/innobase/fil/fil0fil.cc

@@ -8683,6 +8683,8 @@ dberr_t fil_tablespace_iterate(const Encryption_metadata &encryption_metadata,
   ut::aligned_free(page);
   ut::free(filepath);
 
+  block->page.reset_page_id();
+
   mutex_free(&block->mutex);
 
   ut::free(block);