Zlib: Use defines for inffast

Zlib's inffast uses a handful of magic numbers. It would be easier to
read and maintain if these magic numbers were instead #defines.

NigelTao@ wrote this code to clean up the magic numbers in
https://chromium-review.googlesource.com/c/chromium/src/+/601694

Nigel gave me permission to make a separate pull request to separate out
just the magic number cleaning.

BUG=764431

Change-Id: I0a62e31e98d4f3afcc64bd096e62a4b4b175644b
Reviewed-on: https://chromium-review.googlesource.com/663424
Commit-Queue: Chris Blume <cblume@google.com>
Reviewed-by: Adenilson Cavalcanti <cavalcantii@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#502982}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 5d7c2b78db0e96c769dee8d4ed3a9aeac8ef21d5

1 files changed, 2 insertions, 1 deletions

diff --git a/inflate.c b/inflate.c
index 69b769a..bec9497 100644
--- a/inflate.c
+++ b/inflate.c
@@ -1043,7 +1043,8 @@ int flush;
         case LEN_:
             state->mode = LEN;
         case LEN:
-            if (have >= 6 && left >= 258) {
+            if (have >= INFLATE_FAST_MIN_HAVE &&
+                left >= INFLATE_FAST_MIN_LEFT) {
                 RESTORE();
                 inflate_fast(strm, out);
                 LOAD();