For all those stuck with a similar problem, run the following:
LD_LIBRARY_PATH=/usr/local/lib64/:$LD_LIBRARY_PATH
export LD_LIBRARY_PATH
When you compile and install GCC it does put the libraries here but that's it. As the FAQs say ( http://gcc.gnu.org/onlinedocs/libstdc++/faq.html#faq.how_to_set_paths ) you need to add it.
I assumed "How do I insure that the dynamically linked library will be found? " meant "how do I make sure it is always found" not "it wont be found, you need to do this"
For those who don't bother setting a prefix, it is /usr/local/lib64
You can find this mentioned briefly when you install gcc if you read the make output:
Libraries have been installed in:
/usr/local/lib/../lib32
If you ever happen to want to link against installed libraries
in a given directory, LIBDIR, you must either use libtool, and
specify the full pathname of the library, or use the `-LLIBDIR'
flag during linking and do at least one of the following:
- add LIBDIR to the `LD_LIBRARY_PATH' environment variable
during execution
- add LIBDIR to the `LD_RUN_PATH' environment variable
during linking
- use the `-Wl,-rpath -Wl,LIBDIR' linker flag
- have your system administrator add LIBDIR to `/etc/ld.so.conf'
See any operating system documentation about shared libraries for
more information, such as the ld(1) and ld.so(8) manual pages.
Grr that was simple! Also "if you ever happen to want to link against the installed libraries" - seriously?