Update skia to use ifdefs for Vulkan code instead of dummy header

Bug: skia:6721
Change-Id: I80a4c9f2acc09c174497f625c50ed12a8bb76505
Reviewed-on: https://skia-review.googlesource.com/19547
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
diff --git a/gn/find_headers.py b/gn/find_headers.py
index 8cff31d..1baca2f 100755
--- a/gn/find_headers.py
+++ b/gn/find_headers.py
@@ -24,10 +24,10 @@
 
 headers = []
 for directory in include_dirs:
-  for d, _, files in os.walk(directory):
-    for f in files:
+  for f in os.listdir(directory):
+    if os.path.isfile(os.path.join(directory, f)):
       if f.endswith('.h') and f not in blacklist:
-        headers.append(os.path.join(d,f))
+        headers.append(os.path.join(directory,f))
 headers.sort()
 
 with open(skia_h, "w") as f: