Changes to fix the memorytexture regression
Fixes: #6260, that the memoytexture test is failing on big-endian architectures. This patch has the code changes to restore it on big-endian.
If OpenGL ES on a big-endian system, then using GL_RGBA/GL_UNSIGNED_BYTE, otherwise using GL_BGRA/GL_UNSIGNED_BYTE on little-endian systems and GL_BGRA/GL_UNSIGNED_INT_8_8_8_8_REV on big-endian systems.
we have tested and verified it in s390x.
Edited by Gayathri Berli