build: adjust the linker flags for JavaKit

`-rpath` is not a universally valid flag for the linker. Adjust the
linker flags to add the library search path on Windows and elide the
`-rpath` flag. It is unclear why there is no `server` subdirectory under
`lib` when using the Oracle JDK 23, but this allows us to find the
necessary library.

Author: compnerd

Package.swift

@@ -174,8 +174,10 @@ let package = Package(
             "-rpath",
             "-Xlinker",
             "\(javaHome)/lib/server",
-          ]
+          ],
+          .when(platforms: [.linux, .macOS])
         ),
+        .unsafeFlags(["-L\(javaHome)/lib"], .when(platforms: [.windows])),
         .linkedLibrary("jvm"),
       ]
     ),