Revert "Do not test inferior Swift libraries on Darwin (#5611)" (#5617)

This reverts commit d045aa6.

Author: shahmishal

Utilities/bootstrap

@@ -558,14 +558,6 @@ def add_rpath_for_cmake_build(args, rpath):
     note(' '.join(add_rpath_cmd))
     subprocess.call(add_rpath_cmd, stderr=subprocess.PIPE)
 
-def get_swift_backdeploy_library_paths(args):
-    if platform.system() == 'Darwin':
-        # Need to include backwards compatibility libraries for Concurrency
-        # FIXME: Would be nice if we could get this from `swiftc -print-target-info`
-        return ['/usr/lib/swift', args.target_info["paths"]["runtimeLibraryPaths"][0] + '/../../swift-5.5/macosx']
-    else:
-        return []
-
 def build_swiftpm_with_cmake(args):
     """Builds SwiftPM using CMake."""
     note("Building SwiftPM (with CMake)")
@@ -597,10 +589,6 @@ def build_swiftpm_with_cmake(args):
         add_rpath_for_cmake_build(args, os.path.join(args.build_dirs["swift-system"],          "lib"))
         add_rpath_for_cmake_build(args, os.path.join(args.build_dirs["swift-collections"],     "lib"))
 
-        # rpaths for compatibility libraries
-        for lib_path in get_swift_backdeploy_library_paths(args):
-            add_rpath_for_cmake_build(args, lib_path)
-
 def build_swiftpm_with_swiftpm(args, integrated_swift_driver):
     """Builds SwiftPM using the version of SwiftPM built with CMake."""
 
@@ -696,7 +684,7 @@ def get_swiftpm_env_cmd(args):
     env_cmd.append("SWIFTPM_MACOS_DEPLOYMENT_TARGET=%s" % g_macos_deployment_target)
 
     if args.bootstrap:
-        library_paths = [
+        libs_joined = ":".join([
             os.path.join(args.bootstrap_dir,                       "lib"),
             os.path.join(args.build_dirs["tsc"],                   "lib"),
             os.path.join(args.build_dirs["llbuild"],               "lib"),
@@ -706,14 +694,11 @@ def get_swiftpm_env_cmd(args):
             os.path.join(args.build_dirs["swift-crypto"],          "lib"),
             os.path.join(args.build_dirs["swift-system"],          "lib"),
             os.path.join(args.build_dirs["swift-collections"],     "lib"),
-        ]
+        ] + args.target_info["paths"]["runtimeLibraryPaths"])
 
         if platform.system() == 'Darwin':
-            # Does not include Swift runtime library paths because of rdar://75752698
-            libs_joined = ":".join(library_paths)
             env_cmd.append("DYLD_LIBRARY_PATH=%s" % libs_joined)
         else:
-            libs_joined = ":".join(library_paths + args.target_info["paths"]["runtimeLibraryPaths"])
             env_cmd.append("LD_LIBRARY_PATH=%s" % libs_joined)
 
     return env_cmd
@@ -753,10 +738,6 @@ def get_swiftpm_flags(args):
     # toolchains that include libraries not part of the OS (e.g. PythonKit or
     # TensorFlow).
     if platform.system() == "Darwin":
-        # rpaths for compatibility libraries
-        for lib_path in get_swift_backdeploy_library_paths(args):
-            build_flags.extend(["-Xlinker", "-rpath", "-Xlinker", lib_path])
-
         swift_library_rpath_prefix = "@executable_path/../"
     elif platform.system() == 'Linux' or platform.system() == 'OpenBSD':
         # `$ORIGIN` is an ELF construct.