binderfs: add gitignore for generated sample program

Let's keep "git status" happy and quiet.

Fixes: 9762dc1432e1 ("samples: add binderfs sample program
Fixes: fca5e94921d5 ("samples: binderfs: really compile this sample and fix build issues")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

samples/binderfs/.gitignore

diff --git a/samples/binderfs/.gitignore b/samples/binderfs/.gitignore
new file mode 100644
index 0000000..eb60241
--- /dev/null
+++ b/samples/binderfs/.gitignore
@@ -0,0 +1 @@
+binderfs_example