Undef private *_BODY defines after use

Bug: 14865741
Change-Id: I1398f7b3f64e3c94f2714cede5b61205dfa78a24
diff --git a/libc/include/dirent.h b/libc/include/dirent.h
index bfe4ea4..71eb2e7 100644
--- a/libc/include/dirent.h
+++ b/libc/include/dirent.h
@@ -56,6 +56,8 @@
 struct dirent { __DIRENT64_BODY };
 struct dirent64 { __DIRENT64_BODY };
 
+#undef __DIRENT64_BODY
+
 #define d_fileno d_ino
 
 typedef struct DIR DIR;