Errors when compiling C++ using cross GCC

[Florian Weimer]

* Mark G.:

> Building C++ without -static, however results in the errors below. What's
> odd is that the multiple definition errors in the dynamic libstdc++.so are
> from symbols in the same library.

I'd look at the output from “eu-readelf -s
/opt/cross/lib/gcc/arm-linux-gnueabihf/6.2.0/../../../../arm-linux-gnueabihf/lib/libstdc++.so”
next.  It seems to me it contains a statically-linked copy of libm.a,
which really should not happen.

Since you are using a pre-built sysroot, maybe that's not set up for
dynamic linking at all?