Add more compile checks and resolve warnings

Jan Breuer

2015-04-22 c40ce04acce103186b4a7eceea6d84ea22499c7d

 libscpi/src/units.c

@@ -38,6 +38,7 @@
#include "scpi/parser.h"
#include "scpi/units.h"
#include "utils_private.h"
#include "scpi/utils.h"
#include "scpi/error.h"
#include "lexer_private.h"