Added explicit calls to fstream::close rather than relying on destructors as a tentative gcc-cygwin fix.

[SVN r21287]

example/snippets/regex_search_example.cpp

@@ -103,6 +103,7 @@ int main(int argc, const char** argv)
       map_type m;
       std::ifstream fs(argv[i]);
       load_file(text, fs);
+      fs.close();
       IndexClasses(m, text);
       cout << m.size() << " matches found" << endl;
       map_type::iterator c, d;