Hi,
gcc 5.2 introduce a new ABI (for std::string in particular) and clang has yet to add support for it 
To work around it you need to force gcc 5.2 to use the old ABI either by building gcc 5.2 with:
/usr/src/gcc-5.2.0/configure --with-default-libstdcxx-abi=gcc4-compatible
A more risky solution from gcc.gnu.org/gcc-5/changes.html#libstdcxx
Runtime Library (libstdc++)
A Dual ABI is provided by the library. A new ABI is enabled by default. The old ABI is still supported and can be used by defining the macro _GLIBCXX_USE_CXX11_ABI to 0 before including any C++ standard library headers.
But see the part about “Troubleshooting” in
https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html
Cheers,
Philippe.