Switch check_clang_tidy to argparse and add a -resource-dir argument.

-resource-dir can be used to inject non-standard resource dirs via the
lit site config.

llvm-svn: 251021
diff --git a/clang-tools-extra/test/clang-tidy/readability-identifier-naming.cpp b/clang-tools-extra/test/clang-tidy/readability-identifier-naming.cpp
index a97f8e9b..cd7e461 100644
--- a/clang-tools-extra/test/clang-tidy/readability-identifier-naming.cpp
+++ b/clang-tools-extra/test/clang-tidy/readability-identifier-naming.cpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy %s readability-identifier-naming %t \
+// RUN: %check_clang_tidy %s readability-identifier-naming %t -- \
 // RUN:   -config='{CheckOptions: [ \
 // RUN:     {key: readability-identifier-naming.AbstractClassCase, value: CamelCase}, \
 // RUN:     {key: readability-identifier-naming.AbstractClassPrefix, value: 'A'}, \