[struct_pack] Add support for big-endian platform #639

Job	Run time
ubuntu_clang (Release, OFF, ON)	4m 39s
ubuntu_clang (Release, OFF, OFF)	4m 59s
ubuntu_clang (Debug, OFF, ON)	4m 19s
ubuntu_clang_pb (Release, OFF, ON)	1m 32s
ubuntu_clang_pb (Release, OFF, OFF)	1m 45s
ubuntu_clang (Debug, OFF, OFF)	3m 57s
ubuntu_clang10 (Release)	2m 7s
ubuntu_clang_pb (Debug, OFF, ON)	1m 44s
ubuntu_clang10 (Debug)	1m 35s
ubuntu_clang_pb (Debug, OFF, OFF)	1m 25s
ubuntu_clang_for_liburing (Release, OFF, ON)	4m 1s
ubuntu_clang_for_liburing (Debug, OFF, ON)	3m 18s
	35m 21s

Provide feedback