Fallback for key gen without hard link support (#89) Add a non-atomic fallback for key generation on platforms where link() is not permitted (such as most stock Android installs) or on filesystems without hard link support (such as FAT).

#!/bin/sh

# Wrap all "#define X Y" with a #ifndef X...#endif"

sed 's/^\( *#define \([^ ][^ ]*\) .*\)/#ifndef \2\
\1\
#endif/'