partition.cpp: fix build, add missing include

Change-Id: I5b4c3b90d579573536e9de2df5127160cdc9a10f
diff --git a/partition.cpp b/partition.cpp
index 4626a5f..d038c38 100644
--- a/partition.cpp
+++ b/partition.cpp
@@ -24,6 +24,7 @@
 #include <sys/mount.h>
 #include <unistd.h>
 #include <dirent.h>
+#include <libgen.h>
 #include <iostream>
 #include <sstream>
 #include <sys/param.h>