math/scilab: fix build on powerpc64*

Please check your user-defined functions (or external module ones) should they appear in the stack trace.
Otherwise you can report a bug on http://bugzilla.scilab.org/ with:

• a sample code which reproduces the issue
• the result of [a, b] = getdebuginfo()
• the following information:

[powerpc64le-default-job-11:33162] Signal: Abort trap (6)
[powerpc64le-default-job-11:33162] Signal code: (65543)

PR: 225628