Move all file specific globals to anonymous namespace

libdevcore/SwarmHash.cpp

@@ -24,6 +24,8 @@
 using namespace std;
 using namespace dev;
 
+namespace
+{
 
 bytes toLittleEndian(size_t _size)
 {
@@ -59,6 +61,8 @@ h256 swarmHashIntermediate(string const& _input, size_t _offset, size_t _length)
 	return swarmHashSimple(ref, _length);
 }
 
+}
+
 h256 dev::swarmHash(string const& _input)
 {
 	return swarmHashIntermediate(_input, 0, _input.size());