Fixed error condition.

Author: cincuranet

Provider/src/FirebirdSql.Data.FirebirdClient/Client/Managed/XdrStream.cs

@@ -415,6 +415,7 @@ public byte[] ReadBytes(int count)
 				}
 				if (toRead == count)
 				{
+					_ioFailed = true;
 					throw new IOException();
 				}
 			}
@@ -433,6 +434,7 @@ public async Task<byte[]> ReadBytesAsync(int count)
 				}
 				if (toRead == count)
 				{
+					_ioFailed = true;
 					throw new IOException();
 				}
 			}