Remove unused `#include`s from parser/cutils.c

Looks like these have been unused since
7c665f9c.
21 jobs for master in 119 minutes and 27 seconds (queued for 3 seconds)
Name Stage Failure
failed
validate-x86_64-linux-deb9-debug Build
$ cp -Rf $HOME/.cabal cabal-cache
Uploading artifacts...
ghc-*.tar.xz: found 1 matching files
junit.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=154363 responseStatus=201 Created token=tHzYtd_Y
Uploading artifacts...
junit.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=154363 responseStatus=201 Created token=tHzYtd_Y
ERROR: Job failed: exit code 1