Demos: Add a dynamic linking demo to show off dlfcn methods

The LinkDemo program calls dlopen/dlsym/dlclose to try and load
a dyanmic library from /usr/lib. It read a global variable and
calls a global function (extern "C" of course :) ).

There a few hacks left in the LinkLib dynamic library, however.
In order to get the linker to stop complaining, we have to use
-nostartfiles -ffreestanding otherwise it will link crt0.o to our
shared object, which is definitely not right as the _init function
for a main program (that calls main) is not suitable for our lib

.gitignore

@@ -8,7 +8,7 @@
 *.o
 *.ao
 *.a
-
+*.so
 *.d
 
 *.swp