Print stats on displayed and ignored warnings.

Summary:
Also displays a hint to use -header-filter='.*' in case any warnings
are in non-user code. This will help discoverability of this option.

Reviewers: klimek

Reviewed By: klimek

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D3621

llvm-svn: 208174
diff --git a/clang-tools-extra/test/clang-tidy/nolint.cpp b/clang-tools-extra/test/clang-tidy/nolint.cpp
index f192930..d4a5c4c 100644
--- a/clang-tools-extra/test/clang-tidy/nolint.cpp
+++ b/clang-tools-extra/test/clang-tidy/nolint.cpp
@@ -1,4 +1,4 @@
-// RUN: clang-tidy -checks=google-explicit-constructor -disable-checks='' %s -- | FileCheck %s
+// RUN: clang-tidy -checks=google-explicit-constructor -disable-checks='' %s -- 2>&1 | FileCheck %s
 
 class A { A(int i); };
 // CHECK: :[[@LINE-1]]:11: warning: Single-argument constructors must be explicit [google-explicit-constructor]
@@ -8,3 +8,4 @@
 
 class C { C(int i); }; // NOLINT(we-dont-care-about-categories-yet)
 // CHECK-NOT: :[[@LINE-1]]:11: warning: Single-argument constructors must be explicit [google-explicit-constructor]
+// CHECK: Suppressed 2 warnings (2 NOLINT)