golang/xenlight: init xenlight go module

Initialize the xenlight Go module using the xenbits git-http URL,
xenbits.xenproject.org/git-http/xen.git/tools/golang/xenlight.

Also simplify the build Make target by using `go build` instead of `go
install`, and do not set GOPATH here because it is now unnecessary.

Signed-off-by: Nick Rosbrook <rosbrookn@ainfosec.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>

tools/golang/xenlight/Makefile

@@ -33,7 +33,7 @@ $(XEN_GOPATH)/src/$(XEN_GOCODE_URL)/xenlight/: xenlight.go types.gen.go helpers.
 # so that it can find the actual library.
 .PHONY: build
 build: package
-	CGO_CFLAGS="$(CFLAGS_libxenlight) $(CFLAGS_libxentoollog)" CGO_LDFLAGS="$(LDLIBS_libxenlight) $(LDLIBS_libxentoollog) -L$(XEN_XENLIGHT) -L$(XEN_LIBXENTOOLLOG)" GOPATH=$(XEN_GOPATH) $(GO) install -x $(XEN_GOCODE_URL)/xenlight
+	CGO_CFLAGS="$(CFLAGS_libxenlight) $(CFLAGS_libxentoollog)" CGO_LDFLAGS="$(LDLIBS_libxenlight) $(LDLIBS_libxentoollog) -L$(XEN_XENLIGHT) -L$(XEN_LIBXENTOOLLOG)" $(GO) build -x
 
 .PHONY: install
 install: build

tools/golang/xenlight/go.mod

@@ -0,0 +1 @@
+module xenbits.xenproject.org/git-http/xen.git/tools/golang/xenlight