Access LockCount in a thread safe way

The field .LockCount can be used from different theads at the same
time.

We define it as _Atomic to have atomic accesses to the field and fix a
TSAN warning:
==================
WARNING: ThreadSanitizer: data race (pid=64069)
  Write of size 4 at 0x7b4c00000138 by thread T6 (mutexes: write M0):
    #0 RFUnlockAllSharing PCSC/src/readerfactory.c:1080:23 (pcscd+0xe3f15) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #1 SCardDisconnect PCSC/src/winscard.c:863:7 (pcscd+0xe3f15)
    #2 ContextThread PCSC/src/winscard_svc.c:575:16 (pcscd+0xe64f7) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #3 ContextThread PCSC/src/winscard_svc.c:575:16 (pcscd+0xe64f7) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)

  Previous write of size 4 at 0x7b4c00000138 by thread T3:
    #0 RFSetReaderEventState PCSC/src/readerfactory.c:1304:23 (pcscd+0xdd8f2) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #1 EHStatusHandlerThread PCSC/src/eventhandler.c:362:11 (pcscd+0xd6c9c) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)

  Location is heap block of size 400 at 0x7b4c00000000 allocated by main thread:
    #0 malloc <null> (pcscd+0x52691) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #1 RFAllocateReaderSpace PCSC/src/readerfactory.c:135:25 (pcscd+0xda2e9) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #2 main PCSC/src/pcscdaemon.c:645:7 (pcscd+0xd8465) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)

  Mutex M0 (0x55dc20366908) created at:
    #0 pthread_mutex_lock <null> (pcscd+0x71ada) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #1 RFUnlockAllSharing PCSC/src/readerfactory.c:1076:8 (pcscd+0xe3ecf) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #2 SCardDisconnect PCSC/src/winscard.c:863:7 (pcscd+0xe3ecf)
    #3 ContextThread PCSC/src/winscard_svc.c:575:16 (pcscd+0xe64f7) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #4 ContextThread PCSC/src/winscard_svc.c:575:16 (pcscd+0xe64f7) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)

  Thread T6 (tid=64077, running) created by main thread at:
    #0 pthread_create <null> (pcscd+0x53dfd) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #1 ThreadCreate PCSC/src/utils.c:184:8 (pcscd+0xe3c9b) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #2 CreateContextThread PCSC/src/winscard_svc.c:256:7 (pcscd+0xd924e) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #3 SVCServiceRunLoop PCSC/src/pcscdaemon.c:133:9 (pcscd+0xd924e)
    #4 main PCSC/src/pcscdaemon.c:801:2 (pcscd+0xd8810) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #5 main PCSC/src/pcscdaemon.c:801:2 (pcscd+0xd8810) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)

  Thread T3 (tid=64073, running) created by main thread at:
    #0 pthread_create <null> (pcscd+0x53dfd) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #1 ThreadCreate PCSC/src/utils.c:184:8 (pcscd+0xe3c9b) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #2 EHSpawnEventHandler PCSC/src/eventhandler.c:233:7 (pcscd+0xd6840) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #3 RFAddReader PCSC/src/readerfactory.c:397:8 (pcscd+0xdb6cd) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #4 HPAddDevice PCSC/src/hotplug_libudev.c:512:8 (pcscd+0xe33f9) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #5 HPScanUSB PCSC/src/hotplug_libudev.c:579:3 (pcscd+0xe2a0d) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)
    #6 HPRegisterForHotplugEvents PCSC/src/hotplug_libudev.c:761:2 (pcscd+0xe2a0d)
    #7 main PCSC/src/pcscdaemon.c:768:7 (pcscd+0xd8717) (BuildId: ca24a31c13ced4613b52730b820229170aba90d6)

SUMMARY: ThreadSanitizer: data race PCSC/src/readerfactory.c:1080:23 in RFUnlockAllSharing
==================

src/readerfactory.h

@@ -124,7 +124,7 @@ THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  int port; /**< Port ID */
  int slot; /**< Current Reader Slot */
  _Atomic SCARDHANDLE hLockId; /**< Lock Id */
- int LockCount; /**< number of recursive locks */
+ _Atomic int LockCount; /**< number of recursive locks */
  _Atomic int32_t contexts; /**< Number of open contexts */
  int * pFeeds; /**< Number of shared client to lib */
  int * pMutex; /**< Number of client to mutex */