bfd_set_section_alignment errors

bfd_set_section_alignment errors

I noticed when making the change from "einfo" to "fatal" that the
alignment error in _bfd_elf_link_create_gnu_property_sec lacked a %P,
and then decided that a bfd_set_section_alignment that can't happen
does not merit a separate error message.  elfxx-x86.c had copied the
same code, so fix that too.  In fact, every bfd_set_section_alignment
call in elfxx-x86.c will always return true absent some future
programming error.  This patch makes those that accompany making a
section lose their "failed to align " error and share the "failed to
create" error.  Those that are changing alignment of a section created
elsewhere now abort on bfd_set_section_alignment returning false.