closes https://github.com/assimp/assimp/issues/1722: use a const reference to fix issue with ppc.

code/Bitmap.cpp

@@ -84,7 +84,8 @@ namespace Assimp {
     }
 
     template<typename T>
-    inline std::size_t Copy(uint8_t* data, T& field) {
+    inline 
+    std::size_t Copy(uint8_t* data, const T &field) {
 #ifdef AI_BUILD_BIG_ENDIAN
         T field_swapped=AI_BE(field);
         std::memcpy(data, &field_swapped, sizeof(field)); return sizeof(field);

code/ObjFileMtlImporter.cpp

@@ -52,7 +52,6 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <assimp/material.h>
 #include <assimp/DefaultLogger.hpp>
 
-
 namespace Assimp    {
 
 // Material specific token (case insensitive compare)