FreeBSD: lld does not support -Wl,-z,nodump

Summary:
kstars appends -Wl,-z,nodump to the linker flags, which is not supported by lld>=7 (previous versions just discareded unkonwn flags).

Add cmake module to check for support of the flag. (See also the abandoned D17863).

This should fix the build on FreeBSD CI.

Test Plan: - Should be tested on Linux too.

Reviewers: FreeBSD, KStars, mutlaqja

Reviewed By: KStars, mutlaqja

Subscribers: kde-edu

Tags: KDE Edu

Differential Revision: https://phabricator.kde.org/D25501