rpminspect: adjust disablement for badfuncs

We had something, but apparently it stopped working.
Let's try with a new format:
https://github.com/rpminspect/rpminspect/issues/1229#issuecomment-1673327657

[skip changelog]

rpminspect.yaml

@@ -1,6 +1,9 @@
  # Disable badfuncs check that has tons of false positives.
 badfuncs:
-  exclude_path: .*
+  allowed:
+    /usr/lib/systemd/tests/unit-tests/*:
+       - inet_addr
+       - inet_aton
 
 # don't report changed content of compiled files
 # that is expected with every update