Exclude --as-needed linker flag in darwin + gcc scenario
Exclude --as-needed linker flag in darwin + gcc scenario

A leftover from #1414 that missed testing on #1434.

ipa-rmb/pcl,KevenRing/vlp,mikhail-matrosov/pcl,ipa-rmb/pcl,wgapl/pcl,stefanbuettner/pcl,ipa-rmb/pcl,KevenRing/pcl,damienjadeduff/pcl,kanster/pcl,kanster/pcl,wgapl/pcl,kanster/pcl,wgapl/pcl,KevenRing/vlp,KevenRing/pcl,KevenRing/pcl,lebronzhang/pcl,stefanbuettner/pcl,drmateo/pcl,stefanbuettner/pcl,ipa-rmb/pcl,damienjadeduff/pcl,mikhail-matrosov/pcl,KevenRing/pcl,drmateo/pcl,kanster/pcl,lebronzhang/pcl,damienjadeduff/pcl,mikhail-matrosov/pcl,KevenRing/vlp,stefanbuettner/pcl,mikhail-matrosov/pcl,KevenRing/vlp,KevenRing/vlp,drmateo/pcl,damienjadeduff/pcl,kanster/pcl,ipa-rmb/pcl,lebronzhang/pcl,KevenRing/pcl,stefanbuettner/pcl,wgapl/pcl,drmateo/pcl,lebronzhang/pcl,drmateo/pcl,wgapl/pcl,damienjadeduff/pcl,mikhail-matrosov/pcl,lebronzhang/pcl