Add fuzz.cpp to jsoncpp_test

Author: Google-Autofuzz

meson.build

@@ -88,7 +88,8 @@ jsoncpp_test = executable(
   'jsoncpp_test',
   [ 'src/test_lib_json/jsontest.cpp',
     'src/test_lib_json/jsontest.h',
-    'src/test_lib_json/main.cpp'],
+    'src/test_lib_json/main.cpp',
+    'src/test_lib_json/fuzz.cpp'],
   include_directories : jsoncpp_include_directories,
   link_with : jsoncpp_lib,
   install : false,