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/id/CMakeLists.txt

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

userspace/programs/id/main.cpp

@@ -0,0 +1,36 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <pwd.h>
+
+int main()
+{
+	uid_t uid = getuid();
+	uid_t euid = geteuid();
+
+	gid_t gid = getgid();
+	gid_t egid = getegid();
+
+	passwd* pw_uid = getpwuid(uid);
+	if (pw_uid == nullptr)
+	{
+		fprintf(stderr, "Unknown user #%d\n", uid);
+		return 1;
+	}
+
+	passwd* pw_euid = getpwuid(euid);
+	if (pw_euid == nullptr)
+	{
+		fprintf(stderr, "Unknown user #%d\n", euid);
+		return 1;
+	}
+
+	printf("uid=%u(%s)", uid, pw_uid->pw_name);
+	if (uid != euid)
+		printf(",euid=%u(%s)",euid, pw_euid->pw_name);
+
+	printf(" gid=%u", gid);
+	if (gid != egid)
+		printf(",egid=%u", egid);
+
+	printf("\n");
+}