Add proftool to decode profile data

This tool provides the facility to decode U-Boot trace data and write out
a text file in Linux ftrace format for use with pytimechart.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/.gitignore b/tools/.gitignore
index 9bce719..a7fee26 100644
--- a/tools/.gitignore
+++ b/tools/.gitignore
@@ -9,6 +9,7 @@
 /mxsboot
 /ncb
 /ncp
+/proftool
 /ubsha1
 /xway-swap-bytes
 /*.exe