sys: ioq: implement IRP capacity

inc/winfsp/fsctl.h

@@ -75,6 +75,9 @@ enum
     FspFsctlIrpTimeoutMaximum = 600000,
     FspFsctlIrpTimeoutDefault = 300000,
     FspFsctlIrpTimeoutDebug = 42,       /* special value for IRP timeout testing; debug driver only */
+    FspFsctlIrpCapacityMinimum = 100,
+    FspFsctlIrpCapacityMaximum = 1000,
+    FspFsctlIrpCapacityDefault = 1000,
 };
 typedef struct
 {
@@ -83,6 +86,7 @@ typedef struct
     UINT32 SerialNumber;
     UINT32 TransactTimeout;             /* milliseconds; values between 1 sec and 10 sec */
     UINT32 IrpTimeout;                  /* milliseconds; values between 1 min and 10 min */
+    UINT32 IrpCapacity;                 /* maximum number of pending IRP's */
     UINT32 EaSupported:1;               /* supports extended attributes (unimplemented; set to 0) */
     UINT32 FileNameRequired:1;          /* FileName required for all operations (not just Create) */
     WCHAR Prefix[64];                   /* UNC prefix to recognize (\\server\path format, 0-term) */