classes/recipes: More optimal DISTRO_FEATURES references

Using the contains function results in more optimal sstate checksums
resulting in better cache reuse as we as more consistent code.

(From OE-Core rev: 9c93526756e7cbbff027c88eb972f877bcb1f057)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/perl/perl-ptest.inc

@@ -42,7 +42,7 @@ python populate_packages_prepend() {
     # Put all *.t files from the lib dir in the ptest package
     # do_split_packages requires a pair of () in the regex, but we have nothing
     # to match, so use an empty pair.
-    if "ptest" in d.getVar("DISTRO_FEATURES", True).split():
+    if oe.utils.contains('DISTRO_FEATURES', 'ptest', True, False, d):
         do_split_packages(d, d.expand('${libdir}/perl/${PV}'), '.*\.t()',
             '${PN}-ptest%s', '%s', recursive=True, match_path=True)
 }