readCreateProcessWithExitCode: runInteractiveProcess: exec: resource exhausted (Argument list too long)

[watashi]

This was an regression introduced by #31
The main purpose of xargs was to ensure the command line is never too long to exceed getconf ARG_MAX, which is likely 2M.
To repro:

LONG_DIR=$(echo $(seq 60) | tr ' ' '-')
mkdir $LONG_DIR
for i in $(seq 30000); do echo "foo bar" > $LONG_DIR/$i.hs; done
find -name '*.hs' | wc
#  30000   30000 5448894
retrie --adhoc 'forall x. foo (bar x) = x' -t . -v 2
# retrie: /bin/sh: readCreateProcessWithExitCode: runInteractiveProcess: exec: resource exhausted (Argument list too long)