[fontc] Disable autohinting

If we're identical before autohinting that should be enough for our
purposes, and there was a non-deterministic crash in ttfautohint that
was causing noise in our crater results.

Lib/gftools/builder/fontc.py

@@ -52,6 +52,8 @@ def modify_config(self, config: dict):
             config["buildWebfont"] = False
             config["buildSmallCap"] = False
             config["splitItalic"] = False
+            # disable running ttfautohint, because we had a segfault
+            config["autohintTTF"] = False
             # set --no-production-names, because it's easier to debug
             extra_args = config.get("extraFontmakeArgs") or ""
             extra_args += " --no-production-names --drop-implied-oncurves"