Only add "extern" to const array in C++
Only add "extern" to const array in C++

In C, it warns when an extern is added to a variable definition:
 'rebol_sym_funcs'  initialized and declared 'extern' [-Werror]

While in C++, because the const variables have internal linkage by
default, it requires "extern", or it wouldn't be able to resolve the
symbol.

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