build: Use only meson for squeekboard

This breaks autoconf. The only resulting binary is the squeekboard GUI. It still needs the autotools-built eekboard client in order to do anything useful. That one needs to be built using a different branch, making this a WIP.

eekboard/key-emitter.h

@@ -0,0 +1,31 @@
+#ifndef KEYEMITTER_H
+#define KEYEMITTER_H
+
+#include <glib.h>
+#include <X11/XKBlib.h>
+
+#include "eek/eek.h"
+
+typedef struct {
+    gint group;
+} EekboardContext;
+
+typedef struct {
+    EekboardContext *context;
+    XkbDescRec *xkb;
+    guint modifier_keycodes[8];
+} Client;
+
+void
+emit_key_activated (EekboardContext *context,
+                  guint            keycode,
+                  EekSymbol       *symbol,
+                  guint            modifiers,
+                  Client *client);
+
+gboolean
+client_enable_xtest (Client *client);
+
+void
+client_disable_xtest (Client *client);
+#endif // KEYEMITTER_H