travis: use suppression list to suppress warnings.

.travis.yml

@@ -20,7 +20,7 @@ script:
 # compile cppcheck, default build
   - make -j4
   - make test -j4
-  - ./cppcheck --error-exitcode=1 -Ilib --enable=style --suppress=duplicateBranch cli gui lib build -igui/test
+  - ./cppcheck --error-exitcode=1 -Ilib --enable=style --suppressions-list=.travis_suppressions cli gui lib build -igui/test
 # compile gui
   - cd gui
   - qmake

.travis_suppressions

@@ -0,0 +1,4 @@
+uselessAssignmentPtrArg:build/checkstl.cpp
+assertWithSideEffect:build/checkuninitvar.cpp
+duplicateBranch:build/checkunusedvar.cpp
+duplicateBranch:lib/checkunusedvar.cpp