Add PBD::sys::operator/ to pbd/filesystem for convenient path building

git-svn-id: svn://localhost/ardour2/trunk@2412 d708f5d6-7413-0410-9779-e7cbd77b26cf

libs/pbd/pbd/filesystem.h

@@ -115,6 +115,9 @@ public:
 	int system_error() const { return m_error_code; }
 };
 
+inline path operator/ (const path& lhs, const path& rhs)
+{ return path(lhs) /= rhs; }
+
 /// @return true if path at p exists
 bool exists(const path & p);