Correct a header path for sync.h in libsync

Not all sources lists have been kept up to date with code
movement/removal and it seems to make some isolate steps in
cq sad for some CLs (mine).

Change-Id: I37b2cff42454a5f4c49eb947289c279701639868
Reviewed-on: https://chromium-review.googlesource.com/c/1288972
Reviewed-by: Antoine Labour <piman@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#602773}
diff --git a/third_party/libsync/BUILD.gn b/third_party/libsync/BUILD.gn
index feedae6..6db1a51 100644
--- a/third_party/libsync/BUILD.gn
+++ b/third_party/libsync/BUILD.gn
@@ -27,7 +27,7 @@
 
   source_set("libsync") {
     sources = [
-      "src/include/sync.h",
+      "src/include/sync/sync.h",
       "src/sw_sync.h",
       "src/sync.c",
       "strlcpy.c",