Fix memory leak on `realloc' failure

* libguile/script.c (realloc0): New helper.
  (script_read_arg, scm_get_meta_args): Use realloc0, not realloc.

Signed-off-by: Dmitry Bogatov <KAction@gnu.org>
build: Honor program name transformation in 'guild'.

* configure.ac: Remove erroneous 'guile_program_name' substitute; see
  <https://lists.gnu.org/archive/html/autoconf/2014-04/msg00010.html>
  for details.  Remove 'meta/guild' config file.
* meta/Makefile.am (guild): New target.
  (CLEANFILES): Add 'guild'.
* meta/guild.in: Remove 'prefix' and 'exec_prefix' definitions; use
  @installed_guile@.
build: Clean up rules for meta/{guild,guile-config}.

* meta/Makefile.am (guile-config, guild): Avoid useless 'cat'
  invocation'.  Quote all occurrences of '@'.
  Suggested by Eric Blake <eblake@redhat.com>.
print: avoid triggering deprecation warnings when printing weak vectors.

* libguile/print.c (iprin1): Use 'scm_c_weak_vector_ref' to access
  elements of weak vectors.
Support weak vectors, arrays, and bitvectors in (system base types).

* module/system/base/types.scm (%tc7-wvect, %tc7-array, %tc7-bitvector):
  New variables.
  (cell->object): Add cases for weak vectors, arrays, and bitvectors.