add latest gcc builds

[dellelce]

gcc11 & gcc12 should be built (required by cmake)

[dellelce]

build fails in the following function:

struct objalloc *
objalloc_create (void)
{
  struct objalloc *ret;
  struct objalloc_chunk *chunk;

  ret = (struct objalloc *) malloc (sizeof *ret);
  if (ret == NULL)
    return NULL;

  ret->chunks = (PTR) malloc (CHUNK_SIZE);
  if (ret->chunks == NULL)
    {
      free (ret);
      return NULL;
    }

  chunk = (struct objalloc_chunk *) ret->chunks;
  chunk->next = NULL;
  chunk->current_ptr = NULL;

  ret->current_ptr = (char *) chunk + CHUNK_HEADER_SIZE;
  ret->current_space = CHUNK_SIZE - CHUNK_HEADER_SIZE;

  return ret;
}

[dellelce]

see also:
PR #59

[dellelce]

disabling the build of libiberty I get:

make[3]: *** No rule to make target `../libiberty/libiberty.a', needed by `full-stamp'.  Stop.