ODR-violation found by ASAN:

==17022==ERROR: AddressSanitizer: odr-violation (0x2b86adb17c60):
  [1] size=352 'vtable for emfio::emfreader::XEmfParser' /home/tdf/lode/jenkins/workspace/lo_ubsan/emfio/source/emfuno/xemfparser.cxx
  [2] size=352 'vtable for emfio::emfreader::XEmfParser' /home/tdf/lode/jenkins/workspace/lo_ubsan/emfio/source/emfuno/xemfparser.cxx
These globals were registered at these points:
  [1]:
    #0 0x443a73 in __asan_register_globals /home/tdf/lode/packages/llvm-3.8.0.src/projects/compiler-rt/lib/asan/asan_globals.cc:218
    #1 0x2b86bea2dced in asan.module_ctor (/workdir/LinkTarget/CppunitTest/libtest_emfio_wmf.so+0x1a0ced)
    #2 0x7fff394ad75a  (<unknown module>)

  [2]:
    #0 0x443a73 in __asan_register_globals /home/tdf/lode/packages/llvm-3.8.0.src/projects/compiler-rt/lib/asan/asan_globals.cc:218
    #1 0x2b86ad6e862d in asan.module_ctor (/workdir/LinkTarget/CppunitTest/libtest_emfio_emf.so+0x18862d)
    #2 0x7fff394ad75a  (<unknown module>)

Change-Id: Id98677a3692ac6a0586164aa5d0a2c82ab26f916
Reviewed-on: https://gerrit.libreoffice.org/40029Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Stephan Bergmann <sbergman@redhat.com>