add file reserve Linux OS API for radlink

src/linux/base/linux_base.c

@@ -908,6 +908,13 @@ id_from_file(File file)
   return id;
 }
 
+internal B32
+file_reserve_size(File file, U64 size)
+{
+  int status = fallocate((int)file.u64[0], FALLOC_FL_KEEP_SIZE, 0, size);
+  return status == 0;
+}
+
 internal B32
 delete_file_at_path(String8 path)
 {