find-unneeded-includes: Don't propose functional -> bits/std_function.h

As seen for include/comphelper/doublecheckedinit.hxx - won't compile anyways

Change-Id: I3a0d5e115ecfc61ae90c6e843ecf4f0213b76e82
Reviewed-on: https://gerrit.libreoffice.org/60838
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

bin/find-unneeded-includes

@@ -57,6 +57,7 @@ def ignoreRemoval(include, toAdd, absFileName, moduleRules):
     bits = {
         "exception": "bits/exception.h",
         "memory": "bits/shared_ptr.h",
+        "functional": "bits/std_function.h",
     }
     for k, v in bits.items():
         if include == k and v in toAdd: