Probes for O_NOFOLLOW that compile and run something aren't compatible with cross compiling, so just #define it to 0 if it's not in fcntl.h where posix-2008 says.
diff --git a/Makefile b/Makefile
index c5118e0..40a3426 100644
--- a/Makefile
+++ b/Makefile
@@ -44,9 +44,8 @@
rm -rf toybox toybox_unstripped generated/config.h generated/Config.in \
generated/newtoys.h generated/globals.h testdir \
generated/Config.probed generated/oldtoys.h generated/flags.h \
- generated/portability.h .singleconfig .singleconfig.old \
- generated/instlist generated/mkflags generated/config2help \
- generated/help.h
+ .singleconfig .singleconfig.old generated/help.h \
+ generated/instlist generated/mkflags generated/config2help
distclean: clean
rm -f toybox_old .config*