Introduce openssl backend for v1 and v3 API separation

The main purpose of this is to better handle the API difference and add
an inital work to separate PHP and OpenSSL logic. This is really just
the first step and further changes are coming after that.

Closes GH-16918

Author: bukka

ext/openssl/config.w32

@@ -10,7 +10,7 @@ if (PHP_OPENSSL != "no") {
 	var ret = SETUP_OPENSSL("openssl", PHP_OPENSSL);
 
 	if (ret >= 2) {
-		EXTENSION("openssl", "openssl.c openssl_pwhash.c xp_ssl.c");
+		EXTENSION("openssl", "openssl.c openssl_pwhash.c openssl_backend_common.c openssl_backend_v1.c openssl_backend_v3.c xp_ssl.c");
 		AC_DEFINE("HAVE_OPENSSL_EXT", 1, "Define to 1 if the PHP extension 'openssl' is available.");
 		if (PHP_OPENSSL_LEGACY_PROVIDER != "no") {
 			AC_DEFINE("LOAD_OPENSSL_LEGACY_PROVIDER", 1, "Define to 1 to load the OpenSSL legacy algorithm provider in addition to the default provider.");

ext/openssl/config0.m4

@@ -26,7 +26,7 @@ PHP_ARG_WITH([openssl-argon2],
 
 if test "$PHP_OPENSSL" != "no"; then
   PHP_NEW_EXTENSION([openssl],
-    [openssl.c openssl_pwhash.c xp_ssl.c],
+    [openssl.c openssl_pwhash.c openssl_backend_common.c openssl_backend_v1.c openssl_backend_v3.c xp_ssl.c],
     [$ext_shared])
   PHP_SUBST([OPENSSL_SHARED_LIBADD])
   PHP_SETUP_OPENSSL([OPENSSL_SHARED_LIBADD],