initialize.m: make string operation compatible with PC

PC systems use a backslash as file separator
2 jobs for path_setting in 1 minute and 23 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Test
passed #2691
testsuite_matlab

00:01:23

failed #2692
allowed to fail
testsuite_octave

00:01:11

 
Name Stage Failure
failed
testsuite_octave Test
/home/gitlab-runner/builds/a354a37e/0/Dynare/dseries/src/utilities/x13/printspan.m                                        Unit test number  1  PASS    [ 0.00848198 ]
/home/gitlab-runner/builds/a354a37e/0/Dynare/dseries/src/utilities/x13/printspan.m Unit test number 2 PASS [ 0.00769496 ]
/home/gitlab-runner/builds/a354a37e/0/Dynare/dseries/src/utilities/x13/printspan.m Unit test number 3 PASS [ 0.00717187 ]
/home/gitlab-runner/builds/a354a37e/0/Dynare/dseries/src/utilities/x13/printstart.m Unit test number 1 PASS [ 0.00571418 ]
/home/gitlab-runner/builds/a354a37e/0/Dynare/dseries/src/utilities/x13/setdefaultmember.m Unit test number 1 PASS [ 0.00350785 ]

Makefile:10: recipe for target 'check-octave' failed
make: *** [check-octave] Error 1
ERROR: Job failed: exit status 1