makefile add arm64

Makefile.cross-compiles

@@ -2,7 +2,7 @@ export PATH := $(GOPATH)/bin:$(PATH)
 export GO111MODULE=on
 LDFLAGS := -s -w
 
-os-archs=darwin:amd64 darwin:arm64 freebsd:386 freebsd:amd64 linux:386 linux:amd64 linux:arm windows:386 windows:amd64 linux:mips64 linux:mips64le linux:mips:softfloat linux:mipsle:softfloat
+os-archs=darwin:amd64 darwin:arm64 freebsd:386 freebsd:amd64 linux:386 linux:amd64 linux:arm linux:arm64 windows:386 windows:amd64 linux:mips64 linux:mips64le linux:mips:softfloat linux:mipsle:softfloat
 
 all: build