Huge reworking to get shared libraries (and native replacements) working.

Not there yet, but the framework is pretty close to what I want.

native/msg.c

@@ -0,0 +1,16 @@
+#include "../lx_loader.h"
+
+static uint32 DosPutMessage(uint32 handle, uint32 msglen, const char *msg)
+{
+    // !!! FIXME: this isn't right, but good enough for now.
+    fwrite(msg, msglen, 1, stdout);
+    fflush(stdout);
+    return 0;
+} // DosPutMessage
+
+NATIVE_REPLACEMENT_TABLE("msg")
+    NATIVE_REPLACEMENT(DosPutMessage, 5)
+END_NATIVE_REPLACEMENT_TABLE()
+
+// end of msg.c ...
+