Adding missing command options for zlib_bench

Document the optional compression strategies supported
by zlib_bench.

Bug: 798943
Change-Id: Ic4e1a89163bef087d424467710a016edf5bad242
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2152780
Reviewed-by: Chris Blume <cblume@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Adenilson Cavalcanti <cavalcantii@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#759873}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 2bda34e0848de5ef6181c4de30b88ba89b583cc8
diff --git a/contrib/bench/zlib_bench.cc b/contrib/bench/zlib_bench.cc
index 3a488f2..27c0353 100644
--- a/contrib/bench/zlib_bench.cc
+++ b/contrib/bench/zlib_bench.cc
@@ -307,7 +307,10 @@
 }
 
 void usage_exit(const char* program) {
-  printf("usage: %s gzip|zlib|raw [--compression 0:9] files...\n", program);
+  printf(
+      "usage: %s gzip|zlib|raw [--compression 0:9] [--huffman|--rle] "
+      "files...\n",
+      program);
   exit(1);
 }