pdumper: set DUMP_RELOC_ALIGNMENT_BITS=1 for m68k

pdumper: set DUMP_RELOC_ALIGNMENT_BITS=1 for m68k

Before the change builds would fail like this:

  (...)
  Loading /<<BUILDDIR>>/emacs-27.1+1/debian/build-src/lisp/vc/vc-hooks.el (source)...
  Loading /<<BUILDDIR>>/emacs-27.1+1/debian/build-src/lisp/vc/ediff-hook.el (source)...
  Loading /<<BUILDDIR>>/emacs-27.1+1/debian/build-src/lisp/uniquify.el (source)...
  Loading /<<BUILDDIR>>/emacs-27.1+1/debian/build-src/lisp/electric.el (source)...
  Loading /<<BUILDDIR>>/emacs-27.1+1/debian/build-src/lisp/emacs-lisp/eldoc.el (source)...
  Loading /<<BUILDDIR>>/emacs-27.1+1/debian/build-src/lisp/cus-start.el (source)...
  Loading /<<BUILDDIR>>/emacs-27.1+1/debian/build-src/lisp/tooltip.el (source)...
  Finding pointers to doc strings...
  Finding pointers to doc strings...done
  Dumping under the name bootstrap-emacs.pdmp
  dumping fingerprint: 7b5c59c589dc151eb1e4269bd83fbe809616b5cb9bb5c80014d5b560b391dfb6
  dump relocation out of range

[rlb@defaultvalue.org: create commit message]

Origin: debian
Bug: https://bugs.gnu.org/44531
Bug-Debian: http://bugs.debian.org/1019130
Forwarded: not-needed