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/u8sum/CMakeLists.txt

@@ -0,0 +1,8 @@
+set(SOURCES
+	main.cpp
+)
+
+add_executable(u8sum ${SOURCES})
+banan_link_library(u8sum libc)
+
+install(TARGETS u8sum OPTIONAL)

userspace/programs/u8sum/main.cpp

@@ -0,0 +1,29 @@
+#include <fcntl.h>
+#include <stdio.h>
+
+int main(int argc, char** argv)
+{
+	for (int i = 1; i < argc; i++)
+	{
+		FILE* fp = fopen(argv[i], "r");
+		if (fp == nullptr)
+		{
+			perror("fopen");
+			continue;
+		}
+
+		uint8_t sum = 0;
+
+		uint8_t buffer[1024];
+		while (size_t ret = fread(buffer, 1, sizeof(buffer), fp))
+			for (size_t j = 0; j < ret; j++)
+				sum += buffer[j];
+
+		if (ferror(fp))
+			perror("fread");
+		else
+			printf("%s: %02x\n", argv[i], sum);
+
+		fclose(fp);
+	}
+}