Enable bugprone-assignment-in-if-condition

And fix the one violation.

Change-Id: I8b844d0e987827527c82e3351efd40c1bfd692db
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/.clang-tidy b/.clang-tidy
index da851c0..92c35a8 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -2,6 +2,7 @@
 -*,
 boost-use-to-string,
 bugprone-argument-comment,
+bugprone-assignment-in-if-condition,
 bugprone-assert-side-effect,
 bugprone-bad-signal-to-kill-thread,
 bugprone-bool-pointer-implicit-conversion,