clang-tidy: Enable performance-faster-string-find check

Optimize calls to std::string::find() and friends when the needle
passed is a single character string literal. The character literal
overload is more efficient.

Signed-off-by: George Liu <liuxiwei@ieisystem.com>
Change-Id: I7cfc50410d6b6c9057995df8db47084445119d7b
diff --git a/.clang-tidy b/.clang-tidy
index 190d32f..8a30c2a 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -227,6 +227,7 @@
 modernize-use-transparent-functors,
 modernize-use-uncaught-exceptions,
 modernize-use-using,
+performance-faster-string-find,
 performance-for-range-copy,
 performance-implicit-conversion-in-loop,
 performance-inefficient-algorithm,