Cannot run apps with protobuf 2.6 on Ubuntu 17.10

I have a Qt 5 application which has a dependency on protobuf 2.6.

Having upgraded to Ubuntu 17.10 I am no longer able to run it.

> [libprotobuf FATAL google/protobuf/stubs/common.cc:61] This program requires
> version 3.0.0 of the Protocol Buffer runtime library, but the installed version
> is 2.6.1.
>
> Please update your library.
>
> If you compiled the program yourself, make sure that your headers are from the
> same version of Protocol Buffers as your link-time library.
>
> (Version verification failed in "/build/mir-y44crS/mir-0.28.0+17.10.20171011.1/
> obj-x86_64-linux-gnu/src/protobuf/mir_protobuf.pb.cc".)

When building my app, I am linking against the static version of protobuf, `libprotobuf.a`.

However, by default, protobuf 3 is installed:

    libmirprotobuf3/artful,now 0.28.0+17.10.20171011.1-0ubuntu1 amd64 [installed,automatic]
    libprotobuf-dev/artful,now 3.0.0-9ubuntu5 amd64 [installed]
    libprotobuf-lite10/artful,now 3.0.0-9ubuntu5 amd64 [installed,automatic]
    libprotobuf10/artful,now 3.0.0-9ubuntu5 amd64 [installed,automatic]

A back trace shows the exception originates from `/usr/lib/x86_64-linux-gnu/libmirprotobuf.so.3`.

    #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
    #1 0x00007f56f74e5f5d in __GI_abort () at abort.c:90
    #2 0x00007f56f7e8c095 in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
    #3 0x00007f56f7e89c86 in ?? () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
    #4 0x00007f56f7e89cd1 in std::terminate() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
    #5 0x00007f56f7e89f14 in __cxa_throw () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
    #6 0x000055c570b362c7 in google::protobuf::internal::LogMessage::Finish (this=this@entry=0x7ffe60c10c90) at google/protobuf/stubs/common.cc:195
    #7 0x000055c570b36658 in google::protobuf::internal::LogFinisher::operator= (other=..., this=<optimized out>) at google/protobuf/stubs/common.cc:203
    #8 google::protobuf::internal::VerifyVersion (headerVersion=3000000, minLibraryVersion=<optimized out>, filename=0x7f56e740fb00 "/build/mir-y44crS/mir-0.28.0+17.10.20171011.1/obj-x86_64-linux-gnu/src/protobuf/mir_protobuf.pb.cc") at google/protobuf/stubs/common.cc:61
    #9 0x00007f56e73dd2bb in mir::protobuf::protobuf_AddDesc_mir_5fprotobuf_2eproto() () from /usr/lib/x86_64-linux-gnu/libmirprotobuf.so.3
    #10 0x00007f56e73d0109 in ?? () from /usr/lib/x86_64-linux-gnu/libmirprotobuf.so.3
    #11 0x00007f56f9cd9a6a in call_init (l=<optimized out>, argc=argc@entry=1, argv=argv@entry=0x7ffe60c11c28, env=env@entry=0x7ffe60c11c38) at dl-init.c:72
    #12 0x00007f56f9cd9b7b in call_init (env=0x7ffe60c11c38, argv=0x7ffe60c11c28, argc=1, l=<optimized out>) at dl-init.c:30
    #13 _dl_init (main_map=main_map@entry=0x55c5724d2800, argc=1, argv=0x7ffe60c11c28, env=0x7ffe60c11c38) at dl-init.c:120
    #14 0x00007f56f9cdeb86 in dl_open_worker (a=a@entry=0x7ffe60c11110) at dl-open.c:575
    #15 0x00007f56f7605d64 in __GI__dl_catch_error (objname=objname@entry=0x7ffe60c11100, errstring=errstring@entry=0x7ffe60c11108, mallocedp=mallocedp@entry=0x7ffe60c110ff, operate=operate@entry=0x7f56f9cde7a0 <dl_open_worker>, args=args@entry=0x7ffe60c11110)
        at dl-error-skeleton.c:198
    #16 0x00007f56f9cde0d9 in _dl_open (file=0x55c572496638 "/usr/lib/x86_64-linux-gnu/qt5/plugins/platformthemes/libqgtk3.so", mode=-2147479551, caller_dlopen=0x7f56f840571c, nsid=-2, argc=<optimized out>, argv=<optimized out>, env=0x7ffe60c11c38) at dl-open.c:660
    #17 0x00007f56f5f29ff6 in dlopen_doit (a=a@entry=0x7ffe60c11320) at dlopen.c:66
    #18 0x00007f56f7605d64 in __GI__dl_catch_error (objname=objname@entry=0x55c5724503d0, errstring=errstring@entry=0x55c5724503d8, mallocedp=mallocedp@entry=0x55c5724503c8, operate=operate@entry=0x7f56f5f29fa0 <dlopen_doit>, args=args@entry=0x7ffe60c11320)
        at dl-error-skeleton.c:198
    #19 0x00007f56f5f2a759 in _dlerror_run (operate=operate@entry=0x7f56f5f29fa0 <dlopen_doit>, args=args@entry=0x7ffe60c11320) at dlerror.c:163
    #20 0x00007f56f5f2a092 in __dlopen (file=<optimized out>, mode=<optimized out>) at dlopen.c:87
    #21 0x00007f56f840571c in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
    #22 0x00007f56f83feb45 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
    #23 0x00007f56f83ef068 in QFactoryLoader::instance(int) const () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
    #24 0x00007f56f89b4c23 in QPlatformThemeFactory::create(QString const&, QString const&) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
    #25 0x00007f56f89c2448 in QGuiApplicationPrivate::createPlatformIntegration() () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
    #26 0x00007f56f89c2e3d in QGuiApplicationPrivate::createEventDispatcher() () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
    #27 0x00007f56f8410b85 in QCoreApplicationPrivate::init() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
    #28 0x00007f56f89c48cf in QGuiApplicationPrivate::init() () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
    #29 0x00007f56f9189289 in QApplicationPrivate::init() () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5