.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>

.gitignore

@@ -29,6 +29,7 @@ modules.builtin
 *.bz2
 *.lzma
 *.xz
+*.lz4
 *.lzo
 *.patch
 *.gcno