[json-test] add ROOT::Graf to linked libraries

Required on Windows, keep for general case

Author: linev

roottest/root/io/json/CMakeLists.txt

@@ -13,6 +13,9 @@ ROOTTEST_GENERATE_DICTIONARY(libJsonTestClasses
                   NO_ROOTMAP NO_CXXMODULE
                   FIXTURES_SETUP jsonTestClasses_fixture)
 
+# required only on Windows
+target_link_libraries(libJsonTestClasseslibgen ROOT::Graf)
+
 ROOTTEST_ADD_TEST(BasicTypes
                   MACRO runBasicTypes.C
                   OUTREF BasicTypes.ref