make pendingEntry thread-safe, fixes:
make pendingEntry thread-safe, fixes:

panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x402ef6]
goroutine 1 [running]:
panic(0x602840, 0xc82004c060)
	/usr/lib/go/src/runtime/panic.go:481 +0x3e6
main.main()
	SystemdJournal2Gelf.go:242 +0xb66

react-com/SystemdJournal2Gelf,parse-nl/SystemdJournal2Gelf