BUG #17466: Is it possible to supplement the default compilation options of CFLAGS in configure file？

The following bug has been logged on the website:

Bug reference:      17466
Logged by:          xavier
Email address:      wysunxavier@gmail.com
PostgreSQL version: 14.2
Operating system:   CentOS 7.9
Description:

Hello,
When I try to specify some compilation options in CFLAGS, such as compiling
with macros, when I execute “./configure CFLAGS='-DUSE_TOOLS'”,it will use
'-O0' to compile by default, which is easy to miscompile into a debug
version. I wonder if it is possible to supplement the judgment conditions in
the postgresql source code: If the compilation option is not specified in
CFLAGS, '-O2' is used by default to avoid compiling the wrong debug
version.
I tried making modifications to the configure.ac of master branch.
diff --git a/configure.ac b/configure.ac
index 44d35e1..36e3fc5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -427,6 +427,10 @@ else
   fi
 fi
 
+if [[[ ! $CFLAGS[@] =~ "-O" ]]]; then
+  CFLAGS="$CFLAGS -O2"
+fi
+
 if test "$ac_env_CXXFLAGS_set" = set; then
   CXXFLAGS=$ac_env_CXXFLAGS_value
 elif test "${CXXFLAGS+set}" = set; then