use scm_from_latin1_symboln for string literals and load-symbol

use scm_from_latin1_symboln for string literals and load-symbol

* libguile/bytevectors.c:
* libguile/eval.c:
* libguile/goops.c:
* libguile/i18n.c:
* libguile/load.c:
* libguile/memoize.c:
* libguile/modules.c:
* libguile/ports.c:
* libguile/print.c:
* libguile/procs.c:
* libguile/programs.c:
* libguile/read.c:
* libguile/script.c:
* libguile/srfi-14.c:
* libguile/stacks.c:
* libguile/strings.c:
* libguile/throw.c:
* libguile/vm.c: Use scm_from_latin1_symboln to make symbols from string
  literals, because they aren't in the user's locale -- they are in
  ASCII, and we can optimize this case.

* libguile/vm-i-loader.c: Also use scm_from_latin1_symboln when loading
  narrow symbols.