userspace: Add nologin "shell"

userspace/programs/CMakeLists.txt

@@ -23,6 +23,7 @@ set(USERSPACE_PROGRAMS
 	ls
 	meminfo
 	mkdir
+	nologin
 	nslookup
 	poweroff
 	ProgramLauncher

userspace/programs/nologin/CMakeLists.txt

@@ -0,0 +1,9 @@
+set(SOURCES
+	main.cpp
+)
+
+add_executable(nologin ${SOURCES})
+banan_link_library(nologin ban)
+banan_link_library(nologin libc)
+
+install(TARGETS nologin OPTIONAL)

userspace/programs/nologin/main.cpp

@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+int main()
+{
+	printf("This account is currently not available.\n");
+	return 1;
+}