According to `write.bm', this makes `write' 2.6 times faster for strings.
* libguile/print.c (iprin1): Use `write_character' when
`SCM_WRITINGP (pstate)' and `SCM_CHARP (exp)' or `scm_is_string (exp)'.
(scm_i_charprint): Remove.
(display_character, write_character): New functions.
(scm_write_char): Use `display_character' instead of
`scm_i_charprint'.
* libguile/print.h (scm_i_charprint): Remove declaration.
* benchmark-suite/benchmarks/write.bm: New file.
* benchmark-suite/Makefile.am (SCM_BENCHMARKS): Add
`benchmarks/write.bm'.
