distcheck error for .Plo files

[Mohammad Akhlaghi]

Dear Gnulib maintainers,

I just cloned the most recent commit of Gnulib (549fce0183f02d) to 
bootstrap Gnuastro. However, when running 'make distcheck', I came 
across the following error (in P.S.) for some remaining files after 
'distclean'.

In Gnuastro, all the files under 'bootstrapped/' are managed by Gnulib, 
so I am posting it here.

Cheers,
Mohammad

P.S.

make[2]: Leaving directory '/path/to/build/dir/_build/sub'
rm -f config.status config.cache config.log configure.lineno 
config.status.lineno
rm -f Makefile
ERROR: files left in build directory after distclean:
./bootstrapped/lib/.deps/regex.Plo
./bootstrapped/lib/.deps/vasnprintf.Plo
./bootstrapped/lib/.deps/printf-parse.Plo
./bootstrapped/lib/.deps/getopt.Plo
./bootstrapped/lib/.deps/printf-args.Plo
./bootstrapped/lib/.deps/chdir-long.Plo
./bootstrapped/lib/.deps/fcntl.Plo
./bootstrapped/lib/.deps/mbrtowc.Plo
./bootstrapped/lib/.deps/getopt1.Plo
./bootstrapped/lib/.deps/asnprintf.Plo
make[1]: *** [Makefile:2564: distcleancheck] Error 1
make[1]: Leaving directory '/path/to/build/dir/_build/sub'