[K/N][Tests] Migrate test withSpaces.kt

^KT-61259

native/native.tests/testData/interop/withSpaces/custom headers/custom.h

@@ -0,0 +1,7 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+int custom_strcmp(const char* str1, const char* str2) {
+    return strcmp(str1, str2);
+}