IMPORT: slz: silence a build warning with -Wundef
The test on FIND_OPTIMAL_MATCH for the experimental code can yield a
build warning when using -Wundef, let's turn it into a regular ifdef.
This is slz upstream commit 05630ae8f22b71022803809eb1e7deb707bb30fb
diff --git a/src/slz.c b/src/slz.c
index 8eb0117..9aacb9b 100644
--- a/src/slz.c
+++ b/src/slz.c
@@ -550,7 +550,7 @@
refs[h].by32.word = word;
}
-#if FIND_OPTIMAL_MATCH
+#ifdef FIND_OPTIMAL_MATCH
/* Experimental code to see what could be saved with an ideal
* longest match lookup algorithm. This one is very slow but
* scans the whole window. In short, here are the savings :