ip_utils: fix IP comparaison

Comparing two IP was broken.
If you try "ip1 != ip2" this always return false whatever be
ip1 and ip2.
The operator!= is not called in fact, because ip1 and ip2 were
converted by operator bool() first!

This patch resolves that by:
- mark explicit operator bool()
- declare operator!= as the opposite of operator==

Note: these latest operators have been externalized of the class
as a good C++ practice.

Change-Id: I65d01c391d3871e92bd0d2a49cad3cfa62f698cf
Tuleap: #662

src/ip_utils.h

@@ -104,12 +104,8 @@ public:
             addr.addr.sa_family = AF_UNSPEC;
     }
 
-    inline bool operator==(const IpAddr& other) const {
-        return pj_sockaddr_cmp(&addr, &other.addr) == 0;
-    }
-
     // Is defined
-    inline operator bool() const {
+    inline explicit operator bool() const {
         return isIpv4() or isIpv6();
     }
 
@@ -226,6 +222,10 @@ private:
     pj_sockaddr addr;
 };
 
+// IpAddr helpers
+inline bool operator==(const IpAddr& lhs, const IpAddr& rhs) { return !pj_sockaddr_cmp(&lhs, &rhs); }
+inline bool operator!=(const IpAddr& lhs, const IpAddr& rhs) { return !(lhs == rhs); }
+
 namespace ip_utils {
 
 static const char *const DEFAULT_INTERFACE = "default";