From 75525fcb9f4c7ed1bb39d10aa43ce529c950d208 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Thu, 23 Dec 2021 17:43:12 -0800
Subject: [PATCH] library optimization flag can be selected on command line
 again

`CFLAGS=-O0 make`
will now use `-O0` instead of enforcing `-O3`
which used to be the behavior before introduction of `libzstd.mk`.

This should result in faster tests,
since a few tests depend on this capability for faster roundtrips.
---
 lib/libzstd.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/libzstd.mk b/lib/libzstd.mk
index af12daff..c04957c6 100644
--- a/lib/libzstd.mk
+++ b/lib/libzstd.mk
@@ -79,7 +79,7 @@ endif
   CFLAGS += -fno-stack-protector -fomit-frame-pointer -fno-ident \
             -DDYNAMIC_BMI2=0 -DNDEBUG
 else
-  CFLAGS += -O3
+  CFLAGS ?= -O3
 endif
 
 DEBUGLEVEL ?= 0