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-fork/CMakeLists.txt

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

userspace/tests/test-fork/main.cpp

@@ -0,0 +1,22 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define ERROR(msg) { perror(msg); return 1; }
+#define BUF_SIZE 1024
+
+int main()
+{
+	printf("userspace\n");
+
+	if (fork() == 0)
+	{
+		execl("/usr/bin/cat", "/usr/bin/cat", "/usr/include/kernel/kprint.h", NULL);
+		ERROR("execl");
+		return 0;
+	}
+
+	printf("parent\n");
+	return 0;
+}