pipes: Plug pipe fd leak in "Unable to set a pipe size" error case.

[osctobe]

A trivial fix for error path leaking pipe fds.

[mihalicyn]

LGTM

but please fix https://github.com/checkpoint-restore/criu/pull/2208/checks?check_run_id=14450206848

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: -0.06 ⚠️

Comparison is base (f018893) 70.61% compared to head (18c405c) 70.55%.

❗ Current head 18c405c differs from pull request most recent head 6bcadb7. Consider uploading reports for the commit 6bcadb7 to get more accurate results

Additional details and impacted files

@@             Coverage Diff              @@
##           criu-dev    #2208      +/-   ##
============================================
- Coverage     70.61%   70.55%   -0.06%     
============================================
  Files           133      133              
  Lines         33243    33502     +259     
============================================
+ Hits          23473    23636     +163     
- Misses         9770     9866      +96     

Impacted Files	Coverage Δ
criu/pipes.c	82.44% <0.00%> (ø)

... and 18 files with indirect coverage changes

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