Revert "Work around Windows build failure due to SwiftPM regression."

This reverts commit b03288b.

Author: grynspan

Package.swift

@@ -128,8 +128,6 @@ extension Array where Element == PackageDescription.SwiftSetting {
       .enableExperimentalFeature("AccessLevelOnImport"),
       .enableUpcomingFeature("InternalImportsByDefault"),
 
-      .enableExperimentalFeature("SymbolLinkageMarkers"),
-
       .define("SWT_TARGET_OS_APPLE", .when(platforms: [.macOS, .iOS, .macCatalyst, .watchOS, .tvOS, .visionOS])),
 
       .define("SWT_NO_EXIT_TESTS", .when(platforms: [.iOS, .watchOS, .tvOS, .visionOS, .wasi, .android])),

Sources/Testing/ABI/EntryPoints/ABIEntryPoint.swift

@@ -60,9 +60,6 @@ extension ABIv0 {
 ///
 /// - Returns: The value of ``ABIv0/entryPoint-swift.type.property`` cast to an
 ///   untyped pointer.
-#if hasFeature(SymbolLinkageMarkers)
-@_used
-#endif
 @_cdecl("swt_abiv0_getEntryPoint")
 @usableFromInline func abiv0_getEntryPoint() -> UnsafeRawPointer {
   unsafeBitCast(ABIv0.entryPoint, to: UnsafeRawPointer.self)
@@ -85,9 +82,6 @@ typealias ABIEntryPoint_v0 = @Sendable (
 /// Xcode 16 Beta 1.
 ///
 /// This function will be removed in a future update.
-#if hasFeature(SymbolLinkageMarkers)
-@_used
-#endif
 @available(*, deprecated, message: "Use ABIv0.entryPoint (swt_abiv0_getEntryPoint()) instead.")
 @_cdecl("swt_copyABIEntryPoint_v0")
 @usableFromInline func copyABIEntryPoint_v0() -> UnsafeMutableRawPointer {

cmake/modules/shared/CompilerSettings.cmake

@@ -15,8 +15,6 @@ add_compile_options(
 add_compile_options(
   "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -enable-upcoming-feature -Xfrontend ExistentialAny>"
   "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -enable-upcoming-feature -Xfrontend InternalImportsByDefault>")
-add_compile_options(
-  "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -enable-experimental-feature -Xfrontend SymbolLinkageMarkers>")
 add_compile_options(
   "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-package-name swift_testing>")