Initialize empty slice in golang using idiomatic way

"".main t=1 size=1 args=0x0 locals=0x0
	0x0000 00000 (test_slice_idiomatic.go:3)	TEXT	"".main(SB), $0-0
	0x0000 00000 (test_slice_idiomatic.go:3)	NOP
	0x0000 00000 (test_slice_idiomatic.go:3)	NOP
	0x0000 00000 (test_slice_idiomatic.go:3)	FUNCDATA	$0, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
	0x0000 00000 (test_slice_idiomatic.go:3)	FUNCDATA	$1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
	0x0000 00000 (test_slice_idiomatic.go:5)	RET
	0x0000 c3                                               .
"".init t=1 size=49 args=0x0 locals=0x0
	0x0000 00000 (test_slice_idiomatic.go:6)	TEXT	"".init(SB), $0-0
	0x0000 00000 (test_slice_idiomatic.go:6)	MOVQ	(TLS), CX
	0x0009 00009 (test_slice_idiomatic.go:6)	CMPQ	SP, 16(CX)
	0x000d 00013 (test_slice_idiomatic.go:6)	JLS	42
	0x000f 00015 (test_slice_idiomatic.go:6)	NOP
	0x000f 00015 (test_slice_idiomatic.go:6)	NOP
	0x000f 00015 (test_slice_idiomatic.go:6)	FUNCDATA	$0, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
	0x000f 00015 (test_slice_idiomatic.go:6)	FUNCDATA	$1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
	0x000f 00015 (test_slice_idiomatic.go:6)	MOVBLZX	"".initdone·(SB), AX
	0x0016 00022 (test_slice_idiomatic.go:6)	CMPB	AL, $1
	0x0018 00024 (test_slice_idiomatic.go:6)	JLS	$0, 27
	0x001a 00026 (test_slice_idiomatic.go:6)	RET
	0x001b 00027 (test_slice_idiomatic.go:6)	JNE	$0, 34
	0x001d 00029 (test_slice_idiomatic.go:6)	PCDATA	$0, $0
	0x001d 00029 (test_slice_idiomatic.go:6)	CALL	runtime.throwinit(SB)
	0x0022 00034 (test_slice_idiomatic.go:6)	MOVB	$2, "".initdone·(SB)
	0x0029 00041 (test_slice_idiomatic.go:6)	RET
	0x002a 00042 (test_slice_idiomatic.go:6)	NOP
	0x002a 00042 (test_slice_idiomatic.go:6)	CALL	runtime.morestack_noctxt(SB)
	0x002f 00047 (test_slice_idiomatic.go:6)	JMP	0
	0x0000 64 48 8b 0c 25 00 00 00 00 48 3b 61 10 76 1b 0f  dH..%....H;a.v..
	0x0010 b6 05 00 00 00 00 3c 01 76 01 c3 75 05 e8 00 00  ......<.v..u....
	0x0020 00 00 c6 05 00 00 00 00 02 c3 e8 00 00 00 00 eb  ................
	0x0030 cf                                               .
	rel 5+4 t=15 TLS+0
	rel 18+4 t=14 "".initdone·+0
	rel 30+4 t=7 runtime.throwinit+0
	rel 36+4 t=14 "".initdone·+-1
	rel 43+4 t=7 runtime.morestack_noctxt+0
gclocals·33cdeccccebe80329f1fdbee7f5874cb t=9 dupok size=8
	0x0000 01 00 00 00 00 00 00 00                          ........
"".initdone· t=34 size=1
"".main·f t=9 dupok size=8
	0x0000 00 00 00 00 00 00 00 00                          ........
	rel 0+8 t=1 "".main+0
"".init·f t=9 dupok size=8
	0x0000 00 00 00 00 00 00 00 00                          ........
	rel 0+8 t=1 "".init+0