Make operators == const

Krazy complained about those.

src/libs/utils/environment.h

@@ -50,7 +50,7 @@ public:
     QString value;
     bool unset;
 
-    bool operator==(const EnvironmentItem &other)
+    bool operator==(const EnvironmentItem &other) const
     {
         return (unset == other.unset) && (name == other.name) && (value == other.value);
     }

src/plugins/coreplugin/icontext.h

@@ -66,7 +66,7 @@ public:
     void prepend(int c) { d.prepend(c); }
     void add(const Context &c) { d += c.d; }
     void add(int c) { d.append(c); }
-    bool operator==(const Context &c) { return d == c.d; }
+    bool operator==(const Context &c) const { return d == c.d; }
 
 private:
     QList<int> d;