Unit tests: ensure proper linkage

tstenner · cboulay · commit 29121cf36cdf · 2020-07-21T00:42:29.000-04:00
diff --git a/testing/helper_type.hpp b/testing/helper_type.hpp
@@ -1,5 +1,7 @@
 #pragma once
+extern "C" {
 #include "../include/lsl/common.h"
+}
 #include <string>
 
 template <typename T> struct SampleType {
