libdwfl: linux-proc-maps.c (proc_maps_report): Don't assert on bad input.

If ino == last_ino && dmajor == last_dmajor && dminor == last_dminor then
we expect the file names to be the same as well. Which is reasonable if
the input came from the /proc file system. But there could be bad user
input if the file was supplied through dwfl_linux_proc_maps_report.
Instead of asserting on the bad input, just signal a bad_report.

Signed-off-by: Mark Wielaard <mjw@redhat.com>
Fix abort() on missing section headers.

libdw/
2014-03-03  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Fix abort() on missing section headers.
	* dwarf_begin_elf.c (check_section): Replace abort call by goto err.
	New label err to return NULL.

Signed-off-by: Jan Kratochvil <jan.kratochvil@redhat.com>