Re-add test line that I had thought was useless, but isn't

Justin Fichtner

2017-11-30 e73964b0ad7f080d398251157bd46255b0032783

 libscpi/inc/scpi/expression.h

@@ -41,7 +41,7 @@
#ifdef __cplusplus
extern "C" {
#endif
    

    enum _scpi_expr_result_t {
        SCPI_EXPR_OK = 0,
        SCPI_EXPR_ERROR,