Remove `translit_char`

It has been used only for DOSISH other than Windows.

eval_intern.h

@@ -321,16 +321,4 @@ rb_char_next(const char *p)
 # endif
 #endif
 
-#if defined DOSISH || defined __CYGWIN__
-static inline void
-translit_char(char *p, int from, int to)
-{
-    while (*p) {
-        if ((unsigned char)*p == from)
-            *p = to;
-        p = CharNext(p);
-    }
-}
-#endif
-
 #endif /* RUBY_EVAL_INTERN_H */

ruby.c

@@ -2367,8 +2367,6 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
 
 #ifdef _WIN32
     translit_char_bin(RSTRING_PTR(opt->script_name), '\\', '/');
-#elif defined DOSISH
-    translit_char(RSTRING_PTR(opt->script_name), '\\', '/');
 #endif
 
     ruby_gc_set_params();