libdwfl: Don't call realloc with zero in cu.c addraranges.

Calling realloc when naranges is zero will result is trying to free
aranges. If realloc does free aranges it returns NULL, which means
aranges is still assigned. This is likely not a problem, because in
most cases aranges will be NULL already. But if it was not and
naranges does turn out to be zero after reduction (which would be
invalid DWARF) we are left with a dangling pointer.

Signed-off-by: Mark Wielaard <mark@klomp.org>
2 files changed