Fix -Wclass-memaccess warnings

We want to clear/memset the padding bytes, not just each member,
so using assignment or {} initialization is not an option.

To silence the warnings, cast the object pointer to u8* (which is not
undefined behavior) to make it explicit to the compiler that we want
to fill the object representation.

Source/Core/VideoBackends/Software/SetupUnit.cpp

@@ -25,7 +25,7 @@ void SetupUnit::Init(u8 primitiveType)
 
 OutputVertexData* SetupUnit::GetVertex()
 {
-  memset(m_VertWritePointer, 0, sizeof(*m_VertWritePointer));
+  memset(reinterpret_cast<u8*>(m_VertWritePointer), 0, sizeof(*m_VertWritePointer));
   return m_VertWritePointer;
 }