external/libvisio: -fsanitize=float-divide-by-zero

...when running CppunitTest_writerperfect_draw

Change-Id: I074512f56ebb7eb054c79946c576516036bebbea

external/libvisio/UnpackedTarball_libvisio.mk

@@ -11,8 +11,11 @@ $(eval $(call gb_UnpackedTarball_UnpackedTarball,libvisio))
 
 $(eval $(call gb_UnpackedTarball_set_tarball,libvisio,$(VISIO_TARBALL)))
 
+$(eval $(call gb_UnpackedTarball_set_patchlevel,libvisio,0))
+
 $(eval $(call gb_UnpackedTarball_add_patches,libvisio,\
        external/libvisio/vsd-msvc-max.patch.1 \
+       external/libvisio/ubsan.patch \
 ))
 
 # vim: set noet sw=4 ts=4:

external/libvisio/ubsan.patch

+--- src/lib/VSDParser.cpp
++++ src/lib/VSDParser.cpp
+@@ -1104,7 +1104,11 @@
+   input->seek(1, librevenge::RVNG_SEEK_CUR);
+   double scale = readDouble(input);
+   input->seek(1, librevenge::RVNG_SEEK_CUR);
+-  scale /= readDouble(input);
++  double scaleDenom = readDouble(input);
++  if (scaleDenom != 0)
++  {
++    scale /= scaleDenom;
++  }
+ 
+   if (m_isStencilStarted && m_currentStencil)
+   {