Add explanatory comments around freestanding test configuration

Tackles feedback of the review of #40202

Author: edymtt

test/lit.cfg

@@ -967,6 +967,8 @@ if run_vendor == 'apple':
         if not config.swift_freestanding_is_darwin:
             swift_execution_tests_extra_flags += ' -Xlinker -dead_strip'
 
+        # TODO: consider making the addition of these flags dependent on the CMake
+        # setting for hermetic seal at link
         if not config.swift_freestanding_is_darwin:
             swift_execution_tests_extra_flags += ' -experimental-hermetic-seal-at-link -lto=llvm-full'
 
@@ -980,6 +982,8 @@ if run_vendor == 'apple':
         symlink_if_not_exists("clang", "clang")
         symlink_if_not_exists("shims", "shims")
         symlink_if_not_exists("freestanding", "macosx")
+        # This is needed to allow compiling against Dispatch
+        # TODO: consider making this dependent on swift_enable_dispatch
         if config.swift_freestanding_is_darwin:
             symlink_if_not_exists("apinotes", "apinotes")
         config.resource_dir_opt = "-resource-dir %s" % new_resource_dir