Add *.pftrace in .gitignore

Change-Id: If9fd5dc1a3298f6b4146ca5340db04a863163eb9
diff --git a/.gitignore b/.gitignore
index 6e3d6cd..bb3f624 100644
--- a/.gitignore
+++ b/.gitignore
@@ -29,3 +29,4 @@
 /venv/*
 perf.data*
 TAGS
+/*.pftrace