travis: don't fail a build due to the GCOV job

It fails too often due to installing gcc-7.
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

.travis.yml

@@ -29,6 +29,7 @@ matrix:
     - env: TR_ARCH=fedora-rawhide
     - env: TR_ARCH=fedora-rawhide-aarch64
     - env: TR_ARCH=s390x
+    - env: TR_ARCH=local        GCOV=1
 script:
   - sudo make CCACHE=1 -C scripts/travis $TR_ARCH
 after_success: