ci: Add build with no tests enabled.

This is intended to prevent test-specific code from causing build
failures when no tests are enabled.

Signed-off-by: Philip Tricca <philip.b.tricca@intel.com>
diff --git a/.travis.yml b/.travis.yml
index e471270..799e376 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -64,6 +64,13 @@
   - ./bootstrap
 
 script:
+# build with no tests enabled
+  - mkdir ./build-no-tests
+  - pushd ./build-no-tests
+  - ../configure
+  - make -j$(nproc)
+  - popd
+# build with all tests enabled
   - mkdir ./build
   - pushd ./build
   - |