configure: delete unused `HAVE_OPENSSL3` macro

Closes #14672

.github/scripts/cmp-config.pl

@@ -52,7 +52,6 @@ my %remove = (
     '#define HAVE_LIBSSL 1' => 1,
     '#define HAVE_LIBZSTD 1' => 1,
     '#define HAVE_NGHTTP2_NGHTTP2_H 1' => 1,
-    '#define HAVE_OPENSSL3 1' => 1,
     '#define HAVE_OPENSSL_CRYPTO_H 1' => 1,
     '#define HAVE_OPENSSL_ERR_H 1' => 1,
     '#define HAVE_OPENSSL_PEM_H 1' => 1,

m4/curl-amissl.m4

@@ -52,7 +52,6 @@ if test "$HAVE_PROTO_BSDSOCKET_H" = "1"; then
       LIBS="-lamisslstubs -lamisslauto $LIBS"
       AC_DEFINE(USE_AMISSL, 1, [if AmiSSL is in use])
       AC_DEFINE(USE_OPENSSL, 1, [if OpenSSL is in use])
-      AC_DEFINE_UNQUOTED(HAVE_OPENSSL3, 1, [Define to 1 if using OpenSSL 3 or later.])
       AC_CHECK_HEADERS(openssl/x509.h openssl/rsa.h openssl/crypto.h \
                        openssl/pem.h openssl/ssl.h openssl/err.h)
     ],[

m4/curl-openssl.m4

@@ -322,8 +322,6 @@ if test "x$OPT_OPENSSL" != xno; then
       ]])
     ],[
       AC_MSG_RESULT([yes])
-      AC_DEFINE_UNQUOTED(HAVE_OPENSSL3, 1,
-        [Define to 1 if using OpenSSL 3 or later.])
       ssl_msg="OpenSSL v3+"
     ],[
       AC_MSG_RESULT([no])