[Bug libstdc++/71135] New: rl78-elf libstdc++ FTBFS with some multilibs

["yselkowi at redhat dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71135

            Bug ID: 71135
           Summary: rl78-elf libstdc++ FTBFS with some multilibs
           Product: gcc
           Version: 6.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yselkowi at redhat dot com
  Target Milestone: ---
              Host: x86_64-cygwin
            Target: rl78-elf
             Build: x86_64-cygwin

rl78-elf FTBFS in GCC 6.1 libstdc++-v3 (but not in recent 4.x or 5) due to
r232454:

src/c++11/cow-stdexcept.cc: In function âvoid* txnal_read_ptr(void* const*)â:
src/c++11/cow-stdexcept.cc:274:3: error: static assertion failed: Pointers must
be 32 bits or 64 bits wide
   static_assert(sizeof(uint64_t) == sizeof(void*)
   ^~~~~~~~~~~~~

rl78 has 16-bit pointers.