In LAPACKE tgsen, allocate iwork when ijob = 0. Fixes #772.

[mgates3]

Description
Allocates iwork when ijob = 0. See issue #772.
Before, ijob = 0 segfaults:

lapackpp/test> ./tester --ijob 1,2,3,4,5,0 --dim 10 tgsen
LAPACK++ version 2022.07.00, id c878e31
input: ./tester --ijob '1,2,3,4,5,0' --dim 10 tgsen
                                                                              
type   ijob  jobvl  jobvr       n     error   time (s)  ref time (s)  status  
   d      1  novec  novec      10  0.00e+00   0.000617      0.000517  pass    
   d      2  novec  novec      10  0.00e+00    0.00151       0.00160  pass    
   d      3  novec  novec      10  0.00e+00    0.00405       0.00277  pass    
   d      4  novec  novec      10  0.00e+00    0.00120       0.00121  pass    
   d      5  novec  novec      10  0.00e+00    0.00345       0.00319  pass    
Segmentation fault

After, it passes:

lapackpp/test> ./tester --ijob 1,2,3,4,5,0 --dim 10 tgsen
LAPACK++ version 2022.07.00, id c878e31
input: ./tester --ijob '1,2,3,4,5,0' --dim 10 tgsen
                                                                              
type   ijob  jobvl  jobvr       n     error   time (s)  ref time (s)  status  
   d      1  novec  novec      10  0.00e+00    0.00132       0.00121  pass    
   d      2  novec  novec      10  0.00e+00    0.00272       0.00283  pass    
   d      3  novec  novec      10  0.00e+00    0.00376       0.00300  pass    
   d      4  novec  novec      10  0.00e+00    0.00131       0.00122  pass    
   d      5  novec  novec      10  0.00e+00    0.00314       0.00312  pass    
   d      0  novec  novec      10  0.00e+00   0.000246      0.000236  pass    
All tests passed for tgsen.

Checklist

• The documentation has been updated.
• If the PR solves a specific issue, it is set to be closed on merge.

[langou]

Thanks @mgates3. In addition the comments of xTGSEN read:
IWORK is INTEGER array, dimension (MAX(1,LIWORK))
Yup, we do want IWORK to be allocated in LAPACKE. (In particular since we do write in IWORK(1) as you point out.)