Enable performance-no-int-to-ptr check

We have no violations of this.  Just turn on the check.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: Ie27f5b99fc96b4e61c063bf7979697f3d738744a
diff --git a/.clang-tidy b/.clang-tidy
index 23cc7ae..0027680 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -262,6 +262,7 @@
 performance-move-const-arg,
 performance-move-constructor-init,
 performance-no-automatic-move,
+performance-no-int-to-ptr,
 performance-noexcept-move-constructor,
 performance-trivially-destructible,
 performance-type-promotion-in-math-fn,