Fix memory leak on error path in openssl_open()

`pkey` must be released after it was allocated on the error paths.
Otherwise we get leaks like this:

```
Direct leak of 32 byte(s) in 1 object(s) allocated from:
    #0 0x7ff8d76a1340 in calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:77
    #1 0x7ff8d7189136 in EVP_PKEY_new evp/p_lib.c:385
    #2 0x7ff8d71178e4 in d2i_PrivateKey asn1/a_pkey.c:80
    #3 0x7ff8d719ed07 in PEM_read_bio_PrivateKey pem/pem_pkey.c:135
    #4 0x555c54726e80 in php_openssl_pem_read_bio_private_key /work/php-src/ext/openssl/openssl_backend_v1.c:738
    #5 0x555c5471ee77 in php_openssl_pkey_from_zval /work/php-src/ext/openssl/openssl_backend_common.c:1297
    #6 0x555c54712e3f in zif_openssl_open /work/php-src/ext/openssl/openssl.c:4331
    #7 0x555c554b44e5 in zend_test_execute_internal /work/php-src/ext/zend_test/observer.c:306
    #8 0x555c557dba0b in ZEND_DO_FCALL_SPEC_RETVAL_UNUSED_HANDLER /work/php-src/Zend/zend_vm_execute.h:2024
    php#9 0x555c5593cf57 in execute_ex /work/php-src/Zend/zend_vm_execute.h:116514
    php#10 0x555c55951ec0 in zend_execute /work/php-src/Zend/zend_vm_execute.h:121962
    php#11 0x555c55ab60cc in zend_execute_script /work/php-src/Zend/zend.c:1980
    php#12 0x555c554e8ecb in php_execute_script_ex /work/php-src/main/main.c:2645
    php#13 0x555c554e92db in php_execute_script /work/php-src/main/main.c:2685
    php#14 0x555c55abbc37 in do_cli /work/php-src/sapi/cli/php_cli.c:951
    php#15 0x555c55abe204 in main /work/php-src/sapi/cli/php_cli.c:1362
    php#16 0x7ff8d6d061c9  (/lib/x86_64-linux-gnu/libc.so.6+0x2a1c9) (BuildId: 274eec488d230825a136fa9c4d85370fed7a0a5e)
    php#17 0x7ff8d6d0628a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2a28a) (BuildId: 274eec488d230825a136fa9c4d85370fed7a0a5e)
    php#18 0x555c54609db4 in _start (/work/php-src/build-dbg-asan/sapi/cli/php+0x609db4) (BuildId: 5cc444a6a9fc1a486ea698e72366c16bd5472605)
```

Closes phpGH-21054.

Author: ndossche

ext/openssl/openssl.c

@@ -7507,18 +7507,20 @@ PHP_FUNCTION(openssl_open)
 	cipher = EVP_get_cipherbyname(method);
 	if (!cipher) {
 		php_error_docref(NULL, E_WARNING, "Unknown cipher algorithm");
-		RETURN_FALSE;
+		RETVAL_FALSE;
+		goto out_pkey;
 	}
 
 	cipher_iv_len = EVP_CIPHER_iv_length(cipher);
 	if (cipher_iv_len > 0) {
 		if (!iv) {
 			zend_argument_value_error(6, "cannot be null for the chosen cipher algorithm");
-			RETURN_THROWS();
+			goto out_pkey;
 		}
 		if ((size_t)cipher_iv_len != iv_len) {
 			php_error_docref(NULL, E_WARNING, "IV length is invalid");
-			RETURN_FALSE;
+			RETVAL_FALSE;
+			goto out_pkey;
 		}
 		iv_buf = (unsigned char *)iv;
 	} else {
@@ -7540,8 +7542,9 @@ PHP_FUNCTION(openssl_open)
 	}
 
 	efree(buf);
-	EVP_PKEY_free(pkey);
 	EVP_CIPHER_CTX_free(ctx);
+out_pkey:
+	EVP_PKEY_free(pkey);
 }
 /* }}} */