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/mkdir/CMakeLists.txt

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

userspace/programs/mkdir/main.cpp

@@ -0,0 +1,23 @@
+#include <stdio.h>
+#include <sys/stat.h>
+
+int main(int argc, char** argv)
+{
+	if (argc <= 1)
+	{
+		fprintf(stderr, "Missing operand\n");
+		return 1;
+	}
+
+	int ret = 0;
+	for (int i = 1; i < argc; i++)
+	{
+		if (mkdir(argv[i], 0755) == -1)
+		{
+			perror("mkdir");
+			ret = 1;
+		}
+	}
+
+	return ret;
+}