@x13/run.m: compatibility fix for Octave

Previously, .mdl files would unnecessarily be passed through importdata(),
which crashes on Octave.

The nested “if”s (testing for the output file extension) have been reorganized,
so that importdata() is not called on .mdl files (and neither on .acm and .rcm,
where is not needed either).
4 jobs for master in 2 minutes and 8 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #6477
testsuite_matlab

00:00:43

failed #6480
allowed to fail
testsuite_octave

00:01:19

passed #6478
testsuite_old_matlab

00:00:48

failed #6479
allowed to fail
testsuite_octave

00:01:22

 
Name Stage Failure
failed
testsuite_octave Test
/home/gitlab-runner/builds/2084817d/0/sebastien/dseries/tests/../src/utilities/x13/printoption.m                                      Unit test number  1  PASS    [  0.0234151 ]
/home/gitlab-runner/builds/2084817d/0/sebastien/dseries/tests/../src/utilities/x13/printspan.m Unit test number 1 PASS [ 0.0103049 ]
/home/gitlab-runner/builds/2084817d/0/sebastien/dseries/tests/../src/utilities/x13/printspan.m Unit test number 2 PASS [ 0.00970507 ]
/home/gitlab-runner/builds/2084817d/0/sebastien/dseries/tests/../src/utilities/x13/printspan.m Unit test number 3 PASS [ 0.00917697 ]
/home/gitlab-runner/builds/2084817d/0/sebastien/dseries/tests/../src/utilities/x13/printstart.m Unit test number 1 PASS [ 0.00763416 ]
/home/gitlab-runner/builds/2084817d/0/sebastien/dseries/tests/../src/utilities/x13/setdefaultmember.m Unit test number 1 PASS [ 0.0053339 ]

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