od: default -t f to double precision

[can1357]

uutils od -t f defaults to 4-byte floats when no explicit size is provided. GNU od defaults -t f to sizeof(double) (8 bytes), so values and grouping diverge.

Reproduction Steps

printf '\x00\x00\x80\x3f\x00\x00\x00\x40' | od -An -t f
# Expected (GNU):        2.000000473111868
# Actual (uutils):       1.0000000       2.0000000

Impact

Pipelines that parse od -t f output misinterpret binary data under uutils because element width and decoded values differ from GNU semantics.