Fix for multiple Call find_package() - fix #326

[nische]

Wrap CMSIS_LD_.... with if to check if allready exsists.

This works for me at the moment.

[atsju]

Nothing obvious has been brocken according to CI tests.
I let @Hish15 review the code

[nische]

I think i miss something. After i clear my builds i have some issues. I think i dont get the .ld files in my other buildfolders. I will do some more checks. but im not sure how this linker magic happens :-D

[Hish15]

Hello @nische, what is the status on this ?

[nische]

Hi,
I have a issue that the LD files are missing in the other "solution".
In my tests it works only because the LD files are already there from the past.
I think that's not the big deal but at the moment I don't have time to fix it. I hope I have time in a few weeks.

BR, Nico