lib/nfs/Manager: add Compare(ManagedConnection, ManagedConnection)

Required for Boost 1.61, which uses that overload in a BOOST_ASSERT().

src/lib/nfs/Manager.cxx

@@ -59,6 +59,18 @@ NfsManager::Compare::operator()(const ManagedConnection &a,
 	return result < 0;
 }
 
+inline bool
+NfsManager::Compare::operator()(const ManagedConnection &a,
+				const ManagedConnection &b) const
+{
+	int result = strcmp(a.GetServer(), b.GetServer());
+	if (result != 0)
+		return result < 0;
+
+	result = strcmp(a.GetExportName(), b.GetExportName());
+	return result < 0;
+}
+
 NfsManager::~NfsManager()
 {
 	assert(GetEventLoop().IsInside());

src/lib/nfs/Manager.hxx

@@ -64,6 +64,10 @@ class NfsManager final : IdleMonitor {
 		gcc_pure
 		bool operator()(const ManagedConnection &a,
 				const LookupKey b) const;
+
+		gcc_pure
+		bool operator()(const ManagedConnection &a,
+				const ManagedConnection &b) const;
 	};
 
 	/**