Disabling ~path_hairline in iOS nanobench

Temporary measure to make nanobench succeed.

TBR=borenet
BUG=skia:

Review URL: https://codereview.chromium.org/1144173004

tools/nanobench_flags.py

@@ -73,6 +73,7 @@ def get_args(bot):
     match.append('~patch_grid')  # skia:2847
     match.append('~desk_carsvg')
     match.append('~keymobi')
+    match.append('~path_hairline')
 
   if match:
     args.append('--match')