Connection: Loose Comparison for Port Number in Signatures (#14111)

When WordPress is hosted behind a reverse proxy, we ask site owners to
add a `X-Forwarded-Port` header from the reverse proxy to the origin so
that Jetpack can know what port to use in the signature's input.

We also allow site owners to define `JETPACK_SIGNATURE__HTTPS_PORT` and
`JETPACK_SIGNATURE__HTTP_PORT` constants if adding a header is not
possible.

Often, site owners will add the following snippet to their wp-config.php
to make use of those constants:

```
define( 'JETPACK_SIGNATURE__HTTP_PORT', $_SERVER['SERVER_PORT'] );
define( 'JETPACK_SIGNATURE__HTTPS_PORT', $_SERVER['SERVER_PORT'] );
```

Unfortunately, we broke that snippet in
Automattic/jetpack#13489, since we moved to strict
comparisons in:
* https://github.com/Automattic/jetpack/blob/97cc7bb9b26d4184ba4915efd5928e59d4456b38/packages/connection/legacy/class-jetpack-signature.php#L95
* https://github.com/Automattic/jetpack/blob/97cc7bb9b26d4184ba4915efd5928e59d4456b38/packages/connection/legacy/class-jetpack-signature.php#L102

`$_SERVER['SERVER_PORT']` is a string in most environments, and the new
code demands integers.

Switch back to loose comparison.

composer.json

@@ -0,0 +1,26 @@
+{
+	"name": "automattic/jetpack-sync",
+	"description": "Everything needed to allow syncing to the WP.com infrastructure.",
+	"type": "library",
+	"license": "GPL-2.0-or-later",
+	"require": {
+		"automattic/jetpack-connection": "@dev",
+		"automattic/jetpack-constants": "@dev",
+		"automattic/jetpack-options": "@dev",
+		"automattic/jetpack-roles": "@dev",
+		"automattic/jetpack-status": "@dev"
+	},
+	"autoload": {
+		"classmap": [
+			"src/"
+		]
+	},
+	"repositories": [
+		{
+			"type": "path",
+			"url": "../*"
+		}
+	],
+	"minimum-stability": "dev",
+	"prefer-stable": true
+}