Build: Fix regression test failure w/ ctest -j

The djpeg rgb-islow-icc-cmp test must run after the djpeg rgb-islow
test, since the latter generates testout_rgb_islow.icc.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 96a2a5d..796ed71 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -999,6 +999,8 @@
 
   add_test(djpeg-${libtype}-rgb-islow-icc-cmp
     ${MD5CMP} b06a39d730129122e85c1363ed1bbc9e testout_rgb_islow.icc)
+  set_tests_properties(djpeg-${libtype}-rgb-islow-icc-cmp PROPERTIES
+    DEPENDS djpeg-${libtype}-rgb-islow)
 
   add_bittest(jpegtran icc "-copy;all;-icc;${TESTIMAGES}/test2.icc"
     testout_rgb_islow2.jpg testout_rgb_islow.jpg ${MD5_JPEG_RGB_ISLOW2})