Use trusty cluster of travis

.travis.yml

@@ -1,3 +1,6 @@
+sudo: required
+dist: trusty
+
 language: c
 
 #os:
@@ -16,7 +19,7 @@ before_script:
 script: 
   - mkdir _build
   - cd _build
-  - cmake .. -DCMAKE_INSTALL_PREFIX=../_install -DCMAKE_C_COMPILER=$CC -DENABLE_HIREDIS=ON
+  - cmake .. -DCMAKE_INSTALL_PREFIX=../_install -DCMAKE_C_COMPILER=$CC
   - cmake --build . --target install
 
 compiler: