Add all the Ubuntu LTS streams (Xenial is the default).

Author: notroj

.travis.yml

@@ -23,8 +23,11 @@ matrix:
       env: CONFIG="--enable-maintainer-mode --disable-ipv6"
     - name: Maintainer-mode, -Werror
       env: NOTEST_CFLAGS=-Werror CONFIG="--enable-maintainer-mode"
-    - name: Maintainer-mode, -Werror (Xenial)
-      dist: xenial
+    - name: Maintainer-mode, -Werror (Trusty)
+      dist: trusty
+      env: NOTEST_CFLAGS=-Werror CONFIG="--enable-maintainer-mode"
+    - name: Maintainer-mode, -Werror (Bionic)
+      dist: bionic
       env: NOTEST_CFLAGS=-Werror CONFIG="--enable-maintainer-mode"
     - name: Maintainer-mode, -Werror (Focal)
       dist: focal