libstdc++/8475: hash_map error message at run time about __default_alloc_template/force_new not defined

[Loren James Rittle]

>Maybe 'make install' of gcc could set a default dynamic link library
>path to its install. path?

Just to give you a final response.  The position of the FSF gcc
mainatiners is to not do this for a wide range of reasons.  However,
I'm going to have to ask you to review the manual and past list traffic.