[igraph] igraph-0.4.5 gcc-4.3 build failures

[Neal Becker]

Hi.  I am Fedora maintainer for igraph.  igraph-0.4.5 fails with gcc-4.3.  
Fedora 9 has just switched to building with gcc-4.3.

I fixed one minor problem (need <cstdlib> for exit), but now I hit a couple 
more.  Anyone have patches for gcc-4.3?

The current problem is:
walktrap_graph.cpp: In member function 'void Graph::convert_from_igraph(const 
igraph_t*, const igraph_vector_t*)':
walktrap_graph.cpp:147: error: 'exit' was not declared in this scope
walktrap_graph.cpp:166: error: 'sort' was not declared in this scope
walktrap_graph.cpp: In member function 'long int Graph::memory()':
walktrap_graph.cpp:189: error: 'strlen' was not declared in this scope

I think I fixed exit and strlen, but which 'sort' is this supposed to be?