Build: specify djpeg rgb-islow-icc-cmp test dependencies

[orivej]

This test must run after djpeg rgb-islow which generates testout_rgb_islow.icc.

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Test failure was observed at https://hydra.nixos.org/build/87096374/nixlog/1 (https://hydra.nixos.org/build/87096374) with the output:

 41/151 Test  #45: djpeg-shared-rgb-islow-icc-cmp ....................***Failed    0.11 sec
Could not obtain MD5 sum: No such file or directory

[dcommander]

We do not observe this failure in any of the official libjpeg-turbo builds, which all run make test, so you’re going to have to help me understand why it’s occurring in your environment, how a normal user could encounter the issue, and why your patch is the best general-purpose solution.

[orivej]

We have enabled running ctest tests in parallel by default in NixOS/nixpkgs@70e2b0b (NixOS/nixpkgs#50527). You may reproducible the failure e.g. with ctest -j50.

Normally the add_bittest macro is responsible for making a cmp test be dependent upon running the program: https://github.com/libjpeg-turbo/libjpeg-turbo/blob/2.0.1/CMakeLists.txt#L981-L982:

  macro(add_bittest PROG NAME ARGS OUTFILE INFILE MD5SUM)
    add_test(${PROG}-${libtype}-${NAME}
      ${PROG}${suffix} ${ARGS} -outfile ${OUTFILE} ${INFILE})
    add_test(${PROG}-${libtype}-${NAME}-cmp
      ${MD5CMP} ${MD5SUM} ${OUTFILE})
    set_tests_properties(${PROG}-${libtype}-${NAME}-cmp PROPERTIES
      DEPENDS ${PROG}-${libtype}-${NAME})

It makes djpeg rgb-islow-cmp run after djpeg rgb-islow. djpeg rgb-islow-icc-cmp is a manually added test that should also run after djpeg rgb-islow. My patch applies to it the same set_tests_properties invocation.