directories that don't contain any library files shouldn't be added to $LD_LIBRARY_PATH

[stdweird]

not a bug, just a bit confusing sometimes.

not sure what pattern th elinker looks for, but i guess files with name lib* or somthing like that

[boegel]

We could add a check to only add lib directories that contain files (or files starting with lib*) to $LD_LIBRARY_PATH, but we have to be a bit careful with this...

There may not be files present yet when generating the temporary module file before installing extensions for example, but lib* files may get added when installing extensions.

For the final module file (non-fake mode), a check like this should be OK?

[bartoldeman]

This relates to
#3145
although we were mostly discussing header files there.

as a second check one could also check for *.so* files that don't necessarily start with lib