Test different build configurations on Travis.

.travis.yml

@@ -1,6 +1,11 @@
 language: go
 sudo: required
 dist: trusty
+env:
+  - GOTAGS=
+  - GOTAGS=libsqlite3
+  - GOTAGS=trace
+  - GOTAGS=libsqlite3 trace
 go:
   - 1.5
   - 1.6
@@ -10,4 +15,4 @@ before_install:
   - go get golang.org/x/tools/cmd/cover
 script:
   - $HOME/gopath/bin/goveralls -repotoken 3qJVUE0iQwqnCbmNcDsjYu1nh4J4KIFXx
-  - go test -race -v . -tags "libsqlite3"
+  - go test -race -v . -tags "$GOTAGS"