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/cat-mmap/CMakeLists.txt

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

userspace/programs/cat-mmap/main.cpp

@@ -0,0 +1,66 @@
+#include <fcntl.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+bool cat_file(int fd)
+{
+	struct stat st;
+	if (fstat(fd, &st) == -1)
+	{
+		perror("stat");
+		return false;
+	}
+
+	void* addr = mmap(nullptr, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+	if (addr == MAP_FAILED)
+	{
+		perror("mmap");
+		return false;
+	}
+
+	ssize_t nwrite = write(STDOUT_FILENO, addr, st.st_size);
+	if (nwrite == -1)
+		perror("write");
+
+	if (static_cast<uint8_t*>(addr)[st.st_size - 1] != '\n')
+		if (write(STDOUT_FILENO, "\n", 1) == -1)
+			perror("write");
+
+	if (munmap(addr, st.st_size) == -1)
+	{
+		perror("munmap");
+		return false;
+	}
+
+	return true;
+}
+
+int main(int argc, char** argv)
+{
+	int ret = 0;
+
+	if (argc > 1)
+	{
+		for (int i = 1; i < argc; i++)
+		{
+			int fd = open(argv[i], O_RDONLY);
+			if (fd == -1)
+			{
+				perror(argv[i]);
+				ret = 1;
+				continue;
+			}
+			if (!cat_file(fd))
+				ret = 1;
+			close(fd);
+		}
+	}
+	else
+	{
+		if (!cat_file(STDIN_FILENO))
+			ret = 1;
+	}
+
+	return ret;
+}