exiv2 fails on Tiger: error: invalid conversion from 'char**' to 'const char**'

[barracuda156]

In file included from /opt/local/include/gcc7/c++/memory:80:0,
                 from /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/exiv2-0.27.5/include/exiv2/config.h:99,
                 from /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/exiv2-0.27.5/src/convert.cpp:29:
/opt/local/include/gcc7/c++/bits/unique_ptr.h:51:28: note: declared here
   template<typename> class auto_ptr;
                            ^~~~~~~~
In file included from /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/exiv2-0.27.5/src/convert.cpp:34:0:
/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/exiv2-0.27.5/include/exiv2/xmp_exiv2.hpp:149:14: warning: 'template<class> class std::auto_ptr' is deprecated [-Wdeprecated-declarations]
         std::auto_ptr<Impl> p_;
              ^~~~~~~~
In file included from /opt/local/include/gcc7/c++/memory:80:0,
                 from /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/exiv2-0.27.5/include/exiv2/config.h:99,
                 from /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/exiv2-0.27.5/src/convert.cpp:29:
/opt/local/include/gcc7/c++/bits/unique_ptr.h:51:28: note: declared here
   template<typename> class auto_ptr;
                            ^~~~~~~~
/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/exiv2-0.27.5/src/convert.cpp: In function 'bool {anonymous}::convertStringCharsetIconv(std::string&, const char*, const char*)':
/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/exiv2-0.27.5/src/convert.cpp:1552:31: error: invalid conversion from 'char**' to 'const char**' [-fpermissive]
                               &inptr,
                               ^~~~~~
In file included from /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/exiv2-0.27.5/src/convert.cpp:56:0:
/opt/local/include/iconv.h:82:15: note:   initializing argument 2 of 'size_t libiconv(libiconv_t, const char**, size_t*, char**, size_t*)'
 extern size_t iconv (iconv_t cd, const char* * inbuf, size_t *inbytesleft, char* * outbuf, size_t *outbytesleft);
               ^
make[2]: *** [src/CMakeFiles/exiv2lib.dir/convert.cpp.o] Error 1
make[2]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/build'
make[1]: *** [src/CMakeFiles/exiv2lib.dir/all] Error 2
make[1]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/build'
make: *** [all] Error 2
make: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/build'
Command failed:  cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_exiv2/exiv2/work/build" && /usr/bin/make -j1 -w all VERBOSE=ON 
Exit code: 2
Error: Failed to build exiv2: command execution failed