Disable generated file check for libs

They cause too many failures for target_os="win".

BUG=571731

Review URL: https://codereview.chromium.org/1549483003

Cr-Original-Commit-Position: refs/heads/master@{#367603}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: f0f095bd29216918bffaaa381d6d568d51a0e87f
diff --git a/tools/gn/target.cc b/tools/gn/target.cc
index bec13c9..49a22fc 100644
--- a/tools/gn/target.cc
+++ b/tools/gn/target.cc
@@ -554,10 +554,8 @@
     CheckSourceGenerated(file);
   for (const SourceFile& file : inputs_)
     CheckSourceGenerated(file);
-  for (size_t i = 0; i < all_libs_.size(); i++) {
-    if (all_libs_[i].is_source_file())
-      CheckSourceGenerated(all_libs_[i].source_file());
-  }
+  // TODO(agrieve): Check all_libs_ here as well (those that are source files).
+  // http://crbug.com/571731
 }
 
 void Target::CheckSourceGenerated(const SourceFile& source) const {