From e0db3f8a25c20a247a0b49ca00dd6c973b6a16e0 Mon Sep 17 00:00:00 2001
From: laanwj <126646+laanwj@users.noreply.github.com>
Date: Wed, 2 Feb 2022 16:46:13 +0100
Subject: [PATCH] build: Replace use of deprecated autoconf macro
 AC_PROG_CC_C89

According to [autoconf 2.70](https://www.gnu.org/software/autoconf/manual/autoconf-2.70/html_node/Obsolete-Macros.html)
documentation, the `AC_PROG_CC_C89' is replaced by `AC_PROG_CC`, which
defines the same variable `ac_cv_prog_cc_c89`.

Avoids the following message:
```
configure.ac:23: warning: The macro `AC_PROG_CC_C89' is obsolete.
```

Also, remove deprecated `AM_PROG_CC_C_O`.
---
 configure.ac | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index 92e497d..6f1cd62 100644
--- a/configure.ac
+++ b/configure.ac
@@ -38,8 +38,7 @@ AC_PATH_TOOL(AR, ar)
 AC_PATH_TOOL(RANLIB, ranlib)
 AC_PATH_TOOL(STRIP, strip)
 
-AM_PROG_CC_C_O
-AC_PROG_CC_C89
+AC_PROG_CC
 if test x"$ac_cv_prog_cc_c89" = x"no"; then
   AC_MSG_ERROR([c89 compiler support required])
 fi