Add stub for openssl_sign() function

conf/config.neon

@@ -201,6 +201,7 @@ parameters:
 		- ../stubs/arrayFunctions.stub
 		- ../stubs/core.stub
 		- ../stubs/typeCheckingFunctions.stub
+		- ../stubs/openssl.stub
 	earlyTerminatingMethodCalls: []
 	earlyTerminatingFunctionCalls: []
 	memoryLimitFile: %tmpDir%/.memory_limit

stubs/core.stub

@@ -328,3 +328,17 @@
  * @return ($string is lowercase-string ? lowercase-string : string)
  */
 function rtrim(string $string, string $characters = " \n\r\t\v\x00"): string {}
+
+/**
+ * @param array|string $command
+ * @param array $descriptor_spec
+ * @param array &$pipes
+ * @param string|null $cwd
+ * @param array|null $env_vars
+ * @param array|null $options
+ *
+ * @param-out string $pipes
+ *
+ * @return resource|false
+ */
+function proc_open(array|string $command, array $descriptor_spec, &$pipes, ?string $cwd, ?array $env_vars, ?array $options) {}

stubs/openssl.stub

@@ -0,0 +1,18 @@
+<?php
+
+/**
+ * @param string $data
+ * @param string &$signature
+ * @param \OpenSSLAsymmetricKey|\OpenSSLCertificate|string $private_key
+ * @param string|int $algorithm
+ *
+ * @param-out string $signature
+ *
+ * @return bool
+ */
+function openssl_sign(
+    string $data,
+    string &$signature,
+    \OpenSSLAsymmetricKey|\OpenSSLCertificate|string $private_key,
+    string|int $algorithm = OPENSSL_ALGO_SHA1
+): bool {}