use std:: namespace for most cmath functions:

http://en.cppreference.com/w/cpp/header/cmath

code/GenVertexNormalsProcess.cpp

@@ -204,7 +204,7 @@ bool GenVertexNormalsProcess::GenMeshVertexNormals (aiMesh* pMesh, unsigned int
 	// Slower code path if a smooth angle is set. There are many ways to achieve
 	// the effect, this one is the most straightforward one.
 	else	{
-		const float fLimit = ::cos(configMaxAngle); 
+		const float fLimit = std::cos(configMaxAngle);
 		for (unsigned int i = 0; i < pMesh->mNumVertices;++i)	{
 			// Get all vertices that share this one ...
 			vertexFinder->FindPositions( pMesh->mVertices[i] , posEpsilon, verticesFound);