Deadlock for FdManager::fd_manager_lock && FdEntity::fdent_lock when write data concurrently

[Roay]

s3fs version : master

The First :
s3fs_write -> 'autoent.GetExistFdEntity' -> 'FdManager::get()->GetExistFdEntity'
first lock: FdManager::fd_manager_lock [line: 659 in fdcache.cpp]
sec lock: FdEntity::fdent_lock [line: 361 in fdcache_entity.cpp]
The Second :
s3fs_write -> 'ent->Write()' -> 'WriteMixMultipart()' -> 'NoCacheLoadAndPost' -> 'ChangeEntityToTempPath'
first lock: FdEntity::fdent_lock [line: 2088 in fdcache_entity.cpp]
sec lock: FdManager::fd_manager_lock [line: 780 in fdcache.cpp]

[Roay]

#Triggered fix deadlock in clean up cache