[WASM] Resolve build failure by fixing cross compile issue on build-script

The added lines by Apple Silicon patch really depend on the build
machine platform and it forces that we can build stdlib only for
darwin targets. So I changed to allow non-darwin targets and filter only
unsupported darwin targets. This patch shuold be sent to upstream.

Author: kateinoigakukun

utils/build-script

@@ -354,16 +354,15 @@ def apply_default_arguments(toolchain, args):
 
     # Filter out any macOS stdlib deployment targets that are not supported
     # by the macOS SDK.
-    if platform.system() == "Darwin":
-        targets = StdlibDeploymentTarget.get_targets_by_name(
-            args.stdlib_deployment_targets)
-        args.stdlib_deployment_targets = [
-            target.name
-            for target in targets
-            if (target.platform.is_darwin and
-                target.platform.sdk_supports_architecture(
-                    target.arch, args.darwin_xcrun_toolchain))
-        ]
+    targets = StdlibDeploymentTarget.get_targets_by_name(
+        args.stdlib_deployment_targets)
+    args.stdlib_deployment_targets = [
+        target.name
+        for target in targets
+        if (not target.platform.is_darwin or
+            target.platform.sdk_supports_architecture(
+                target.arch, args.darwin_xcrun_toolchain))
+    ]
 
     # Include the Darwin module-only architectures in the CMake options.
     if args.swift_darwin_module_archs: