Fix compilation for MSVC14. (#5490)

- std::min/max were not defined in StackAllocator.inl; Also added explicit template arguments to break macro expansion if Windows.h is included prior and NOMINMAX macro is not present.
- Made static_assert statements compatible with C++11 in ProcessHelper.cpp.
- Removed unused string_view include in ObjFileParser.cpp.

code/AssetLib/Obj/ObjFileParser.cpp

@@ -52,7 +52,6 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <cstdlib>
 #include <memory>
 #include <utility>
-#include <string_view>
 
 namespace Assimp {