Add diagnose option "-Wno-stringop-overflow" option to avoid the comp…

…iling error on gcc9

Add "-Wno-stringop-overflow" option to avoid the following error:

    orch.cpp: In member function 'ref_resolve_status Orch::resolveFieldRefArray(type_map&, const string&, swss::KeyOpFieldsValuesTuple&, std::vector<long unsigned int>&, std::string&)':
    orch.cpp:609:41: error: 'strlen' argument missing terminating nul [-Werror=stringop-overflow=]
      609 |                     object_name_list += string(&list_item_delimiter);
          |                                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
    In file included from orch.cpp:6:
    orch.h:25:12: note: referenced argument declared here
       25 | const char list_item_delimiter = ',';
          |            ^~~~~~~~~~~~~~~~~~~
    cc1plus: all warnings being treated as errors

According to CauldronDevelopmentLLC/cbang#29, this is an error from boost and can be suppressed by using this option

Signed-off-by: Stephen Sun <stephens@nvidia.com>

configure.ac

@@ -83,6 +83,7 @@ CFLAGS_COMMON+=" -Wvariadic-macros"
 CFLAGS_COMMON+=" -Wno-switch-default"
 CFLAGS_COMMON+=" -Wno-long-long"
 CFLAGS_COMMON+=" -Wno-redundant-decls"
+CFLAGS_COMMON+=" -Wno-stringop-overflow"
 
 AC_SUBST(CFLAGS_COMMON)