use libblkid to get filesystem type
we can now use libblkid to detect exfat
diff --git a/libblkid/exec_shell.h b/libblkid/exec_shell.h
new file mode 100644
index 0000000..a2aa757
--- /dev/null
+++ b/libblkid/exec_shell.h
@@ -0,0 +1 @@
+extern void __attribute__((__noreturn__)) exec_shell(void);