Fix find_link_library in the event the linker flag check fails.

[WildCard65]

This small pull request fixes the issue #1113 by doing 2 things:

1. Actually pass the library name being searched for to find_library
2. Use unique variables when invoking find_library in order to avoid any shenanigans older CMake versions may pull (unlikely, but better to be safe than sorry).

[WildCard65]

@microsoft-github-policy-service agree

[daanx]

Hi @WildCard65 , thanks for the fix, but can you make this PR against the dev branch ? (I tried to change the base but it would pull in all other kinds of changes). If this is not easy, I can apply it manually myself as well -- let me know