liblzma: Use 512 as INDEX_GROUP_SIZE.
This lets compiler use shifting instead of 64-bit division.
diff --git a/src/liblzma/common/index.c b/src/liblzma/common/index.c
index 3941e28..ddb9d36 100644
--- a/src/liblzma/common/index.c
+++ b/src/liblzma/common/index.c
@@ -18,7 +18,7 @@
///
/// This should be big enough to avoid making lots of tiny allocations
/// but small enough to avoid too much unused memory at once.
-#define INDEX_GROUP_SIZE 500
+#define INDEX_GROUP_SIZE 512
/// \brief How many Records can be allocated at once at maximum
