.travis.yml: split default config into system and user

As the build times have risen we keep timing out. Split the default
config into system and user builds.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

.travis.yml

@@ -49,7 +49,8 @@ env:
     - TEST_CMD="make check"
     - MAKEFLAGS="-j3"
   matrix:
-    - CONFIG=""
+    - CONFIG="--disable-system"
+    - CONFIG="--disable-user"
     - CONFIG="--enable-debug --enable-debug-tcg"
     - CONFIG="--disable-linux-aio --disable-cap-ng --disable-attr --disable-brlapi --disable-uuid --disable-libusb"
     - CONFIG="--enable-modules --disable-linux-user"