Some slg libraries violates the C++ One Definition Rule on 2.8alpha1

[luyatshimbalanga]

The build system from Fedora reported a violation of C++ One Definition Rule within the SLG libraries. See build.log with the following extract:

builddir/build/BUILD/LuxCore-luxcorerender_v2.8alpha1/redhat-linux-build/generated/luxparser/luxparse.hpp:139:34: warning: ‘luxcore_parserlxs_yylval’ violates the C++ One Definition Rule [-Wodr]
  139 | extern LUXCORE_PARSERLXS_YYSTYPE luxcore_parserlxs_yylval;
      |                                  ^
/builddir/build/BUILD/LuxCore-luxcorerender_v2.8alpha1/redhat-linux-build/generated/luxparser/luxparse.cpp:1728:9: note: type ‘union LUXCORE_PARSERLXS_YYSTYPE’ itself violates the C++ One Definition Rule
 1728 | YYSTYPE yylval;

Affected version: LuxCore 2.8 alpha1

Tested on development branch of Fedora running on GCC 13 root.log with built dependency