Massage LANG to lang.IBM437 to avoid UTF-8 weirdness.

No system seems to actually install en_??.IBM437, but that's what it should
be called, and it falls back to C so good enough I guess.

src/syncterm/conn_pty.c

@@ -389,7 +389,7 @@ int pty_connect(struct bbslist *bbs)
 {
 	struct winsize ws;
 	struct termios ts;
-	char	*termcap;
+	char	*termcap, *lang, *slang, *dot;
 	int	cols, rows;
 
 	ts.c_iflag = TTYDEF_IFLAG;
@@ -442,6 +442,19 @@ int pty_connect(struct bbslist *bbs)
 		termcap=xp_asprintf("%d",ws.ws_row);
 		setenv("LINES",termcap,1);
 		xp_asprintf_free(termcap);
+		setenv("MM_CHARSET", "IBM437", 1);
+		lang = getenv("LANG");
+		if (lang) {
+			slang = strdup(lang);
+			dot = strchr(slang, '.');
+			if (slang && dot) {
+				*dot = 0;
+				lang = xp_asprintf("%s.IBM437", slang);
+				setenv("LANG", lang, 1);
+				xp_asprintf_free(lang);
+				free(slang);
+			}
+		}
 		if(bbs->addr[0])
 			execl("/bin/sh", "/bin/sh", "-c", bbs->addr, (char *)0);
 		else {