The previous commit left confdata writing out:

The previous commit left confdata writing out:

CONFIG_NUMERIC_CONSTANT=

And on reading it back in, it would complain that '' was an invalid value for
that field.  I.E. "make allnoconfig && make" worked fine, but
"make allnoconfig && make menuconfig" barfed reading in the config file.

So now I have it write out "0" as the blank value.  (It's initialized to the
default value when the menu becomes visible anyway; I checked.)  That seems
to work.