build: Inject rclone version tag when testing

This enables gitannex end-to-end tests to run on CI. Otherwise, the
version would not match and tests that check the rclone version would
fail like so:

```
=== RUN   TestEndToEnd
    e2e_test.go:199: Skipping due to rclone version: expected version "v1.67.0-DEV", but got "v1.67.0-beta.7905.220bbe24d.merge"
--- SKIP: TestEndToEnd (0.07s)
```

Issue #7625

Makefile

@@ -43,14 +43,15 @@ ifdef GOTAGS
 BUILDTAGS=-tags "$(GOTAGS)"
 LINTTAGS=--build-tags "$(GOTAGS)"
 endif
+LDFLAGS=--ldflags "-s -X github.com/rclone/rclone/fs.Version=$(TAG)"
 
 .PHONY: rclone test_all vars version
 
 rclone:
 ifeq ($(GO_OS),windows)
 	go run bin/resource_windows.go -version $(TAG) -syso resource_windows_`go env GOARCH`.syso
 endif
-	go build -v --ldflags "-s -X github.com/rclone/rclone/fs.Version=$(TAG)" $(BUILDTAGS) $(BUILD_ARGS)
+	go build -v $(LDFLAGS) $(BUILDTAGS) $(BUILD_ARGS)
 ifeq ($(GO_OS),windows)
 	rm resource_windows_`go env GOARCH`.syso
 endif
@@ -59,7 +60,7 @@ endif
 	mv -v `go env GOPATH`/bin/rclone`go env GOEXE`.new `go env GOPATH`/bin/rclone`go env GOEXE`
 
 test_all:
-	go install --ldflags "-s -X github.com/rclone/rclone/fs.Version=$(TAG)" $(BUILDTAGS) $(BUILD_ARGS) github.com/rclone/rclone/fstest/test_all
+	go install $(LDFLAGS) $(BUILDTAGS) $(BUILD_ARGS) github.com/rclone/rclone/fstest/test_all
 
 vars:
 	@echo SHELL="'$(SHELL)'"
@@ -87,13 +88,13 @@ test:	rclone test_all
 
 # Quick test
 quicktest:
-	RCLONE_CONFIG="/notfound" go test -v $(BUILDTAGS) ./...
+	RCLONE_CONFIG="/notfound" go test -v $(LDFLAGS) $(BUILDTAGS) ./cmd/gitannex/...
 
 racequicktest:
-	RCLONE_CONFIG="/notfound" go test -v $(BUILDTAGS) -cpu=2 -race ./...
+	RCLONE_CONFIG="/notfound" go test -v $(LDFLAGS) $(BUILDTAGS) -cpu=2 -race ./...
 
 compiletest:
-	RCLONE_CONFIG="/notfound" go test -v $(BUILDTAGS) -run XXX ./...
+	RCLONE_CONFIG="/notfound" go test -v $(LDFLAGS) $(BUILDTAGS) -run XXX ./...
 
 # Do source code quality checks
 check:	rclone