Add %check_clang_tidy and %clang_tidy_diff.

With this, site specific lit configs can inject parameters into the
test scripts if they need site specific parameters.

Next up: enable check_clang_tidy to take a resource dir to enable
non-standard locations for builtin includes.

llvm-svn: 251010
diff --git a/clang-tools-extra/test/clang-tidy/readability-uniqueptr-delete-release.cpp b/clang-tools-extra/test/clang-tidy/readability-uniqueptr-delete-release.cpp
index 8fb7562..aa8ae25 100644
--- a/clang-tools-extra/test/clang-tidy/readability-uniqueptr-delete-release.cpp
+++ b/clang-tools-extra/test/clang-tidy/readability-uniqueptr-delete-release.cpp
@@ -1,4 +1,4 @@
-// RUN: %python %S/check_clang_tidy.py %s readability-uniqueptr-delete-release %t
+// RUN: %check_clang_tidy %s readability-uniqueptr-delete-release %t
 
 namespace std {
 template <typename T>