Add imgui.ini to .gitignore

This file is auto-generated by viewer's GUI library (to remember size and
position of windows).

BUG=skia:

Change-Id: Id363301d71d3df1d665c4e495a0d5062cdbc472b
Reviewed-on: https://skia-review.googlesource.com/9095
Reviewed-by: Brian Osman <brianosman@google.com>
1 file changed