ofz: infinite loop

Change-Id: Ie2148fd0048c6894e1b317dd2a4f2533ff2e1814
Reviewed-on: https://gerrit.libreoffice.org/45827Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

starmath/source/mathtype.cxx

@@ -2749,6 +2749,8 @@ void MathType::HandleEmblishments()
     do
     {
         pS->ReadUChar( nEmbel );
+        if (!pS->good())
+            break;
         switch (nEmbel)
         {
         case 0x02: