Update x/sys module to support Risc-V (#32)

go.mod

@@ -8,5 +8,7 @@ require (
 	github.com/stretchr/testify v1.2.2
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
 	github.com/valyala/fasttemplate v0.0.0-20170224212429-dcecefd839c4
-	golang.org/x/sys v0.0.0-20181217223516-dcdaa6325bcb // indirect
+	golang.org/x/sys v0.0.0-20190531175056-4c3a928424d2 // indirect
 )
+
+go 1.13

go.sum

@@ -12,5 +12,5 @@ github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6Kllzaw
 github.com/valyala/bytebufferpool v1.0.0/go.mod h1:6bBcMArwyJ5K/AmCkWv1jt77kVWyCJ6HpOuEn7z0Csc=
 github.com/valyala/fasttemplate v0.0.0-20170224212429-dcecefd839c4 h1:gKMu1Bf6QINDnvyZuTaACm9ofY+PRh+5vFz4oxBZeF8=
 github.com/valyala/fasttemplate v0.0.0-20170224212429-dcecefd839c4/go.mod h1:50wTf68f99/Zt14pr046Tgt3Lp2vLyFZKzbFXTOabXw=
-golang.org/x/sys v0.0.0-20181217223516-dcdaa6325bcb h1:zzdd4xkMwu/GRxhSUJaCPh4/jil9kAbsU7AUmXboO+A=
-golang.org/x/sys v0.0.0-20181217223516-dcdaa6325bcb/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190531175056-4c3a928424d2 h1:T5DasATyLQfmbTpfEXx/IOL9vfjzW6up+ZDkmHvIf2s=
+golang.org/x/sys v0.0.0-20190531175056-4c3a928424d2/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=