BuildSystem: Cleanup userspace directory layout

userspace programs are now in userspace/programs
userspace tests are now in userspace/tests

This makes listing userspace projects much cleaner. Libraries were
already separated to their own directory, so other programs should also.

userspace/tests/test-globals/main.cpp

@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+struct foo_t
+{
+	foo_t() { printf("global constructor works\n"); }
+	~foo_t() { printf("global destructor works\n"); }
+};
+
+foo_t foo;
+
+int main()
+{
+
+}