swift_import: always link the import.

`swift_library` is also moving in this direction.

SwiftPM works by linking all the .o files, so this should end up in a state
that seem users familiar with SwiftPM/Xcode will expect. Otherwise an `@objc`
class might not be findable by name only, or a protocol conformance might not
get included leading to confusing runtime problems.

PiperOrigin-RevId: 527908878

swift/swift_import.bzl

@@ -72,6 +72,7 @@ def _swift_import_impl(ctx):
     libraries_to_link = [
         cc_common.create_library_to_link(
             actions = ctx.actions,
+            alwayslink = True,
             cc_toolchain = swift_toolchain.cc_toolchain_info,
             feature_configuration = get_cc_feature_configuration(
                 feature_configuration,