.gitignore: ignore *.lz4 files

Now that lz4 kernel compression is available, add *.lz4 to .gitignore.

Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Acked-by: Kyungsik Lee <kyungsik.lee@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/.gitignore b/.gitignore
index 3b8b9b3..7e9932e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -29,6 +29,7 @@
 *.bz2
 *.lzma
 *.xz
+*.lz4
 *.lzo
 *.patch
 *.gcno