StripCtrlChars: option to provide a target Terminal.

If you use the new stripctrl_new_term() to construct a StripCtrlChars
instead of the existing stripctrl_new(), then the resulting object
will align itself with the character-set configuration of the Terminal
object you point it at. (In fact, it'll reuse the same actual
translation code, courtesy of the last few refactoring commits.) So it
will interpret things as control characters precisely if that Terminal
would also have done so.

The previous locale-based sanitisation is appropriate if you're
sending the sanitised output to an OS terminal device managed outside
this process - the LC_CTYPE setting has the best chance of knowing how
that terminal device will interpret a byte stream. But I want to start
using the same sanitisation system for data intended for PuTTY's own
internal terminal emulator, in which case there's no reason why
LC_CTYPE should be expected to match that terminal's configuration,
and no reason to need it to either since we can check the internal
terminal configuration directly.

One small bodge: stripctrl_new_term() is actually a macro, which
passes in the function pointer term_translate() to the underlying real
constructor. That's just so that console-only tools can link in
stripctrl.c without acquiring a dependency on terminal.c (similarly to
how we pass random_read in to the mp_random functions).

misc.h

@@ -379,6 +379,12 @@ struct StripCtrlChars {
 };
 StripCtrlChars *stripctrl_new(
     BinarySink *bs_out, bool permit_cr, wchar_t substitution);
+StripCtrlChars *stripctrl_new_term_fn(
+    BinarySink *bs_out, bool permit_cr, wchar_t substitution,
+    Terminal *term, unsigned long (*translate)(
+        Terminal *, term_utf8_decode *, unsigned char));
+#define stripctrl_new_term(bs, cr, sub, term) \
+    stripctrl_new_term_fn(bs, cr, sub, term, term_translate)
 void stripctrl_free(StripCtrlChars *sanpub);
 char *stripctrl_string_ptrlen(ptrlen str);
 static inline char *stripctrl_string(const char *str)