Fix file close crash

[dineshflock]

Fixes file close crash seen only on iOS 13

Fatal Exception: NSFileHandleOperationException
*** -[NSConcreteFileHandle synchronizeFile]: No such file or directory

Fatal Exception: NSFileHandleOperationException
0  CoreFoundation                 0x1af63d344 (Missing)
1  libobjc.A.dylib                0x1af352cc0 (Missing)
2  Foundation                     0x1af9e0050 (Missing)
3  Foundation                     0x1af9dfac0 (Missing)
4  Foundation                     0x1af9a369c (Missing)
5  XCGLogger                      0x10665cf80 FileDestination.rotateFile(to:closure:) + 138 (FileDestination.swift:138)
6  XCGLogger                      0x106653f28 AutoRotatingFileDestination.rotateFile() + 237 (AutoRotatingFileDestination.swift:237)
7  XCGLogger                      0x10665a57c closure #1 in BaseQueuedDestination.output(logDetails:message:) + 41 (BaseQueuedDestination.swift:41)
8  XCGLogger                      0x10665a320 BaseQueuedDestination.output(logDetails:message:) + 48 (BaseQueuedDestination.swift:48)
9  XCGLogger                      0x1066585cc BaseDestination.process(logDetails:) + 124 (BaseDestination.swift:124)
10 XCGLogger                      0x106659dbc protocol witness for DestinationProtocol.process(logDetails:) in conformance BaseDestination (<compiler-generated>)
11 XCGLogger                      0x1066698e8 XCGLogger.logln(_:functionName:fileName:lineNumber:userInfo:closure:) + 348 (XCGLogger.swift:348)
12 XCGLogger                      0x10666955c XCGLogger.logln(_:functionName:fileName:lineNumber:userInfo:closure:) + 325 (XCGLogger.swift:325)
13 XCGLogger                      0x10666b240 XCGLogger.verbose(_:functionName:fileName:lineNumber:userInfo:)
14 XCGLogger                      0x10666a850 XCGLogger.verbose(_:functionName:fileName:lineNumber:userInfo:)

[yourshinsuke]

however iOS 14 can't use XCGLogger now.

@DaveWoodCom

Can you fix?

[dineshflock]

however iOS 14 can't use XCGLogger now.

@yourshinsuke
Though this discussion is unrelated to this pr, but still, may I know why?