Only create objcCompile task on macOS, fails on Windows in IDE (#360)

skiko/build.gradle.kts

@@ -711,9 +711,10 @@ val linkJvmBindings = tasks.register<LinkSkikoTask>("linkJvmBindings") {
     flags.set(listOf(*osFlags))
 }
 
-// Very hacky way to compile Objective-C sources and add the
-// resulting object files into the final library.
-project.tasks.register<Exec>("objcCompile") {
+if (hostOs == OS.MacOS) {
+    // Very hacky way to compile Objective-C sources and add the
+    // resulting object files into the final library.
+    project.tasks.register<Exec>("objcCompile") {
         val inputDir = "$projectDir/src/jvmMain/objectiveC/${targetOs.id}"
         val outDir = "$buildDir/objc/$target"
         val names = File(inputDir).listFiles()!!.map { it.name.removeSuffix(".mm") }
@@ -738,6 +739,7 @@ project.tasks.register<Exec>("objcCompile") {
         file(outDir).mkdirs()
         inputs.files(srcs)
         outputs.files(outs)
+    }
 }
 
 val generateVersion = project.tasks.register("generateVersion") {