Lint on pkg/* packages

- pkg/useragent
- pkg/units
- pkg/ulimit
- pkg/truncindex
- pkg/timeoutconn
- pkg/term
- pkg/tarsum
- pkg/tailfile
- pkg/systemd
- pkg/stringutils
- pkg/stringid
- pkg/streamformatter
- pkg/sockets
- pkg/signal
- pkg/proxy
- pkg/progressreader
- pkg/pools
- pkg/plugins
- pkg/pidfile
- pkg/parsers
- pkg/parsers/filters
- pkg/parsers/kernel
- pkg/parsers/operatingsystem

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

signal/signal_linux.go

@@ -4,6 +4,7 @@ import (
 	"syscall"
 )
 
+// SignalMap is a map of Linux signals.
 var SignalMap = map[string]syscall.Signal{
 	"ABRT":   syscall.SIGABRT,
 	"ALRM":   syscall.SIGALRM,