add pathops debugging to fuzz

Add optional debugging routines for use in gdb.

R=kjlubick
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2171773002

Review-Url: https://codereview.chromium.org/2171773002
diff --git a/gyp/fuzz.gyp b/gyp/fuzz.gyp
index 7290780..a2d1ade 100644
--- a/gyp/fuzz.gyp
+++ b/gyp/fuzz.gyp
@@ -11,13 +11,18 @@
         'defines': [
           'SK_FUZZ_LOGGING',
         ],
-        'sources': [ '<!@(python find.py ../fuzz "*.cpp")' ],
+        'sources': [
+          '<!@(python find.py ../fuzz "*.cpp")',
+          '../tests/PathOpsDebug.cpp',
+        ],
         'dependencies': [
             'flags.gyp:flags',
             'skia_lib.gyp:skia_lib',
         ],
         'include_dirs': [
+            '../include/private',
             '../src/core',
+            '../src/pathops',
         ],
     }],
 }