Simulation may fail under Windows when using external C libraries

[pstelzig]

Problem description

Describe the bug
Users report that under Windows simulation in the test may fail if the Modelica model that shall be tested uses an external "C" library. They report that the simulation binary cannot find the external C library. The problem appears not to exist under Linux.

To Reproduce
A minimum working example to reproduce the bug will be constructed in the comments to this issue.

System information (please complete the following information):

• OS: Windows 11
• OpenModelica version: >= 1.21
• Python version: unknown
• MoPyRegtest version: v0.5.0

Additional context
Users report that under Windows, when compiling a Modelica model the OpenModelica compiler omc creates a .bat file alongside the .exe with the simulation binary. The issue only occurs if the .exe is executed, but not if the .bat file is used.

Desired behavior

• Regression tests defined with MoPyRegtest have to work both under Windows and Linux if the Modelica model under test uses external "C" libraries.
• A unit test shall be created from the minimum working example to ensure working of the fix