Ensure sass.hpp is included before system headers

Without this, system headers on Solaris will export the SEC macro, which
clashes with the SEC constant defined in src/units.hpp.

See 4599662.

src/fn_colors.cpp

@@ -1,3 +1,4 @@
+#include "sass.hpp"
 #include <cctype>
 #include <iomanip>
 #include "ast.hpp"

src/fn_numbers.cpp

@@ -1,3 +1,5 @@
+#include "sass.hpp"
+
 #include <cstdint>
 #include <cstdlib>
 #include <cmath>
@@ -8,7 +10,6 @@
 #include <algorithm>
 
 #include "ast.hpp"
-#include "sass.hpp"
 #include "units.hpp"
 #include "fn_utils.hpp"
 #include "fn_numbers.hpp"

src/fn_strings.cpp

@@ -1,7 +1,7 @@
+#include "sass.hpp"
 #include <cctype>
 #include "utf8.h"
 #include "ast.hpp"
-#include "sass.hpp"
 #include "fn_utils.hpp"
 #include "fn_strings.hpp"
 

src/listize.hpp

@@ -1,6 +1,8 @@
 #ifndef SASS_LISTIZE_H
 #define SASS_LISTIZE_H
 
+#include "sass.hpp"
+
 #include <vector>
 #include <iostream>
 

src/parser.hpp

@@ -1,6 +1,8 @@
 #ifndef SASS_PARSER_H
 #define SASS_PARSER_H
 
+#include "sass.hpp"
+
 #include <string>
 #include <vector>