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/programs/yes/CMakeLists.txt

@@ -0,0 +1,8 @@
+set(SOURCES
+	main.cpp
+)
+
+add_executable(yes ${SOURCES})
+banan_link_library(yes libc)
+
+install(TARGETS yes OPTIONAL)

userspace/programs/yes/main.cpp

@@ -0,0 +1,8 @@
+#include <stdio.h>
+
+int main()
+{
+	for (;;)
+		puts("y");
+	return 0;
+}