Unix: add machine-specific sqrt support.
diff --git a/unix/mpyconfig.h b/unix/mpyconfig.h
index 605b232..f187cbb 100644
--- a/unix/mpyconfig.h
+++ b/unix/mpyconfig.h
@@ -14,3 +14,5 @@
 typedef uint64_t machine_uint_t; // must be pointer size
 typedef void *machine_ptr_t; // must be of pointer size
 typedef double machine_float_t;
+
+machine_float_t machine_sqrt(machine_float_t x);