Undef private *_BODY defines after use

Bug: 14865741
Change-Id: I1398f7b3f64e3c94f2714cede5b61205dfa78a24
diff --git a/libc/include/sys/vfs.h b/libc/include/sys/vfs.h
index cd6044d..5358ffb 100644
--- a/libc/include/sys/vfs.h
+++ b/libc/include/sys/vfs.h
@@ -107,6 +107,8 @@
 struct statfs { __STATFS64_BODY };
 struct statfs64 { __STATFS64_BODY };
 
+#undef __STATFS64_BODY
+
 /* Declare that we have the f_namelen, f_frsize, and f_flags fields. */
 #define _STATFS_F_NAMELEN
 #define _STATFS_F_FRSIZE