cxx version sets off compiler errors

CMakeLists.txt

@@ -314,7 +314,6 @@ if (CIVETWEB_ENABLE_CXX)
   add_cxx_compiler_flag(-Wall)
   add_cxx_compiler_flag(-Wextra)
   add_cxx_compiler_flag(-Wshadow)
-  add_cxx_compiler_flag(-Wsign-conversion)
   add_cxx_compiler_flag(-Wmissing-prototypes)
   add_cxx_compiler_flag(-Weverything)
   add_cxx_compiler_flag(/W4)
@@ -330,7 +329,6 @@ if (CIVETWEB_ENABLE_CXX)
   endif()
   add_cxx_compiler_flag(/WX)
   add_cxx_compiler_flag(-pedantic-errors)
-  add_cxx_compiler_flag(-Wzero-as-null-pointer-constant)
   add_cxx_compiler_flag(-fvisibility=hidden)
   add_cxx_compiler_flag(-fstack-protector-strong RELEASE)
   add_cxx_compiler_flag(-flto RELEASE)