TST: fix `test_fortranfile_read_mixed_record` on big-endian systems
TST: fix `test_fortranfile_read_mixed_record` on big-endian systems

Explicitly request little-endian record reads so this test does not fail
on big-endian platforms (e.g., S390X).

matthew-brett/scipy,WarrenWeckesser/scipy,grlee77/scipy,andyfaff/scipy,anntzer/scipy,e-q/scipy,WarrenWeckesser/scipy,Eric89GXL/scipy,rgommers/scipy,anntzer/scipy,matthew-brett/scipy,WarrenWeckesser/scipy,perimosocordiae/scipy,scipy/scipy,zerothi/scipy,mdhaber/scipy,grlee77/scipy,Stefan-Endres/scipy,vigna/scipy,scipy/scipy,tylerjereddy/scipy,e-q/scipy,rgommers/scipy,grlee77/scipy,ilayn/scipy,Eric89GXL/scipy,Eric89GXL/scipy,perimosocordiae/scipy,scipy/scipy,andyfaff/scipy,mdhaber/scipy,zerothi/scipy,WarrenWeckesser/scipy,Stefan-Endres/scipy,zerothi/scipy,andyfaff/scipy,perimosocordiae/scipy,vigna/scipy,Stefan-Endres/scipy,rgommers/scipy,scipy/scipy,andyfaff/scipy,ilayn/scipy,e-q/scipy,matthew-brett/scipy,vigna/scipy,matthew-brett/scipy,endolith/scipy,e-q/scipy,endolith/scipy,Stefan-Endres/scipy,anntzer/scipy,tylerjereddy/scipy,rgommers/scipy,vigna/scipy,Stefan-Endres/scipy,zerothi/scipy,perimosocordiae/scipy,scipy/scipy,Eric89GXL/scipy,mdhaber/scipy,zerothi/scipy,grlee77/scipy,anntzer/scipy,ilayn/scipy,e-q/scipy,endolith/scipy,endolith/scipy,andyfaff/scipy,Eric89GXL/scipy,ilayn/scipy,endolith/scipy,anntzer/scipy,perimosocordiae/scipy,Eric89GXL/scipy,WarrenWeckesser/scipy,tylerjereddy/scipy,tylerjereddy/scipy,matthew-brett/scipy,WarrenWeckesser/scipy,anntzer/scipy,zerothi/scipy,rgommers/scipy,mdhaber/scipy,tylerjereddy/scipy,mdhaber/scipy,vigna/scipy,grlee77/scipy,ilayn/scipy,perimosocordiae/scipy,endolith/scipy,ilayn/scipy,andyfaff/scipy,Stefan-Endres/scipy,mdhaber/scipy,scipy/scipy