fix: let config reads date their own build

A pin_build that only dates a config_reads entry names the revision the
platform reads that file at (ROCKNIX's armsx2 PKG_VERSION, KNULLI's
lrmame0278), not the profile's source_commit. Since a6716796a wrote
config_reads into the profiles, EveryBuildReferenceNamesThePin counted
armsx2, duckstation, hatari, mame, melonds and xemu as disagreeing. The
value is now required to name the pin only for a profile whose pin
those references hold or follow (pin_frozen, pin_follows).

advancemame still disagrees: held at 799060b, it names three earlier
builds (EmuELEC 6a34ec0, AmberELEC 0f6a767, Recalbox 5f301c8).

tests/test_pin_build.py

@@ -155,7 +155,10 @@ class EveryBuildReferenceNamesThePin(unittest.TestCase):
                 token = value.split()[-1].rsplit("/", 1)[-1].removesuffix(".tar.gz")
                 return value in pins or any(token in v or v in value for v in versions)
 
-            if not any(names_it(str(r["value"])) for r in references):
+            # A reference that only dates a config_reads entry names the build
+            # the platform reads that file at, not this profile's pin.
+            justifies_pin = profile.get("pin_frozen") or profile.get("pin_follows")
+            if justifies_pin and not any(names_it(str(r["value"])) for r in references):
                 disagree.append(name)
             for reference in references:
                 if not cf.pin_build_revision(reference, REPO_ROOT / "platforms"):