Remove ldisc.h.

It only had to be a header file because ldisc.c and ldiscucs.c had to
share the structure definition. But ldiscucs.c vanished a couple of
years ago in commit 71e42b04a5, so it's now fine to make the
Ldisc structure definition local to ldisc.c itself, the way it should
be.

ldisc.c

@@ -11,7 +11,22 @@
 
 #include "putty.h"
 #include "terminal.h"
-#include "ldisc.h"
+
+struct Ldisc_tag {
+    Terminal *term;
+    Backend *backend;
+    Seat *seat;
+
+    /*
+     * Values cached out of conf.
+     */
+    bool telnet_keyboard, telnet_newline;
+    int protocol, localecho, localedit;
+
+    char *buf;
+    size_t buflen, bufsiz;
+    bool quotenext;
+};
 
 #define ECHOING (ldisc->localecho == FORCE_ON || \
                  (ldisc->localecho == AUTO && \

ldisc.h

@@ -1,27 +0,0 @@
-/*
- * ldisc.h: defines the Ldisc data structure used by ldisc.c and
- * ldiscucs.c. (Unfortunately it was necessary to split the ldisc
- * module in two, to avoid unnecessarily linking in the Unicode
- * stuff in tools that don't require it.)
- */
-
-#ifndef PUTTY_LDISC_H
-#define PUTTY_LDISC_H
-
-struct Ldisc_tag {
-    Terminal *term;
-    Backend *backend;
-    Seat *seat;
-
-    /*
-     * Values cached out of conf.
-     */
-    bool telnet_keyboard, telnet_newline;
-    int protocol, localecho, localedit;
-
-    char *buf;
-    size_t buflen, bufsiz;
-    bool quotenext;
-};
-
-#endif /* PUTTY_LDISC_H */