Statically link jaeger into Workhorse by default

This change will statically compile the jaeger client into workhorse
by default. This will allow support staff to enable the
`GITLAB_TRACING` variable to investigate issues further.

Note that by default, this will not enable tracing, only compile the
client in.

Makefile

@@ -14,6 +14,7 @@ VERSION := ${VERSION_STRING}-$(shell date -u +%Y%m%d.%H%M%S)
 GOBUILD := go build -ldflags "-X main.Version=$(VERSION)"
 EXE_ALL := gitlab-zip-cat gitlab-zip-metadata gitlab-workhorse
 INSTALL := install
+BUILD_TAGS := tracer_static tracer_static_jaeger
 
 MINIMUM_SUPPORTED_GO_VERSION := 1.8