protobuf on NetBSD 9

[Stephen Borrill <netbsd%precedence.co.uk@localhost>]

I am trying to build protobuf on NetBSD 9 from pkgsrc-2026Q2 and have 
noted the comments in its Makefile about building with GCC 10 (and it did build 
on NetBSD 10).

It correctly determines it require gcc10 (with gcc10-libs as a runtime 
dependency) to build, but still fails:

In file included from /usr/pkg/gcc10/include/c++/ext/string_conversions.h:43,
                 from /usr/pkg/gcc10/include/c++/bits/basic_string.h:6557,
                 from /usr/pkg/gcc10/include/c++/string:55,
                 from /usr/pkg/gcc10/include/c++/bits/locale_classes.h:40,
                 from /usr/pkg/gcc10/include/c++/bits/ios_base.h:41,
                 from /usr/pkg/gcc10/include/c++/ios:42,
                 from /usr/pkg/gcc10/include/c++/istream:38,
                 from /pkg_comp/obj/pkgsrc/devel/protobuf/default/protobuf-35.1/src/google/protobuf/io/zero_copy_stream_impl.cc:24:
/usr/pkg/gcc10/include/c++/cstdio:176:11: error: 'vfscanf' has not been declared in '::'
  176 |   using ::vfscanf;
      |           ^~~~~~~
/usr/pkg/gcc10/include/c++/cstdio:177:11: error: 'vscanf' has not been declared in '::'
  177 |   using ::vscanf;
      |           ^~~~~~
/usr/pkg/gcc10/include/c++/cstdio:179:11: error: 'vsscanf' has not been declared in '::'
  179 |   using ::vsscanf;
      |           ^~~~~~~
/usr/pkg/gcc10/include/c++/cstdio:186:22: error: 'vfscanf' has not been declared in '__gnu_cxx'
  186 |   using ::__gnu_cxx::vfscanf;
      |                      ^~~~~~~
/usr/pkg/gcc10/include/c++/cstdio:187:22: error: 'vscanf' has not been declared in '__gnu_cxx'
  187 |   using ::__gnu_cxx::vscanf;
      |                      ^~~~~~
/usr/pkg/gcc10/include/c++/cstdio:189:22: error: 'vsscanf' has not been declared in '__gnu_cxx'
  189 |   using ::__gnu_cxx::vsscanf;
      |                      ^~~~~~~
In file included from /pkg_comp/obj/pkgsrc/devel/protobuf/default/.buildlink/include/absl/time/time.h:86,
                 from /pkg_comp/obj/pkgsrc/devel/protobuf/default/.buildlink/include/absl/log/log_entry.h:36,
                 from /pkg_comp/obj/pkgsrc/devel/protobuf/default/.buildlink/include/absl/log/internal/log_message.h:48,
                 from /pkg_comp/obj/pkgsrc/devel/protobuf/default/.buildlink/include/absl/log/internal/strip.h:26,
                 from /pkg_comp/obj/pkgsrc/devel/protobuf/default/.buildlink/include/absl/log/internal/check_op.h:41,
                 from /pkg_comp/obj/pkgsrc/devel/protobuf/default/.buildlink/include/absl/log/internal/check_impl.h:21,
                 from /pkg_comp/obj/pkgsrc/devel/protobuf/default/.buildlink/include/absl/log/absl_check.h:38,
                 from /pkg_comp/obj/pkgsrc/devel/protobuf/default/protobuf-35.1/src/google/protobuf/io/zero_copy_stream_impl.cc:27:
/usr/pkg/gcc10/include/c++/cmath:1089:11: error: 'copysign' has not been declared in '::'
 1089 |   using ::copysign;
      |           ^~~~~~~~
/usr/pkg/gcc10/include/c++/cmath:1093:11: error: 'erf' has not been declared in '::'
 1093 |   using ::erf;
      |           ^~~
/usr/pkg/gcc10/include/c++/cmath:1097:11: error: 'erfc' has not been declared in '::'
 1097 |   using ::erfc;
      |           ^~~~
/usr/pkg/gcc10/include/c++/cmath:1125:11: error: 'hypot' has not been declared in '::'
 1125 |   using ::hypot;
      |           ^~~~~
/usr/pkg/gcc10/include/c++/cmath:1133:11: error: 'lgamma' has not been declared in '::'
 1133 |   using ::lgamma;
      |           ^~~~~~
/usr/pkg/gcc10/include/c++/cmath:1199:11: error: 'scalbln' has not been declared in '::'
 1199 |   using ::scalbln;
      |           ^~~~~~~
/usr/pkg/gcc10/include/c++/cmath:1203:11: error: 'scalbn' has not been declared in '::'
 1203 |   using ::scalbn;
      |           ^~~~~~


--
Stephen