Fix Linux compile error and one failing test

Author: cmcgee1024

.swift-version

@@ -0,0 +1 @@
+main-snapshot-2025-04-12

Sources/Subprocess/Configuration.swift

@@ -871,7 +871,11 @@ internal struct CreatedPipe {
     }
 
     internal init(closeWhenDone: Bool) throws {
+#if os(Windows)
         let pipe = try FileDescriptor.ssp_pipe()
+#else
+        let pipe = try FileDescriptor.pipe()
+#endif
 
         self.readFileDescriptor = .init(
             pipe.readEnd,

Tests/SubprocessTests/SubprocessTests+Unix.swift

@@ -729,7 +729,7 @@ extension SubprocessUnixTests {
         var platformOptions = PlatformOptions()
         platformOptions.supplementaryGroups = Array(expectedGroups)
         let idResult = try await Subprocess.run(
-            .name("/usr/bin/swift"),
+            .name("swift"),
             arguments: [getgroupsSwift.string],
             platformOptions: platformOptions,
             output: .string