#37 Fix for Bug 506627 breaks genxref

[Andrew Beck]

I believe that the fix for Bug 506627 breaks genxref
when trying to index a broken link. Genxref 0.9 worked
fine but when I updated LXR to the development version
on 31/01/2002 it now no longer works on a broken sym
link.
When genxref tries to index the broken sym link it
exits with the following error:

Can't call method "getline" on an undefined value at
LXR/Lang.pm line 44.

I believe this is because line 43 of Lang.pm does not
check that getfilehandle returns a valid file handle.