👷 run sanitizer another time to check if it works

.travis.yml

@@ -49,6 +49,8 @@ matrix:
       apt:
         sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-5.0']
         packages: ['clang-5.0', 'llvm-5.0-dev', 'ninja-build']
+    after_failure:
+      - make clang_sanitize -j4
 
   # cppcheck
   - os: linux

test/CMakeLists.txt

@@ -5,7 +5,7 @@ option(JSON_NoExceptions "Build test suite without exceptions" OFF)
 if(JSON_Sanitizer)
     message(STATUS "Building test suite with Clang sanitizer")
     if(NOT MSVC)
-        set(CMAKE_CXX_FLAGS "-g -O2 -fsanitize=address -fsanitize=undefined -fno-omit-frame-pointer")
+        set(CMAKE_CXX_FLAGS "-std=c++11 -g -O2 -fsanitize=address -fsanitize=undefined -fno-omit-frame-pointer")
     endif()
 endif()