ALL and VITA: Link with GNU Make recursive flag #2727
There are three changes in this PR which are dependent, thus the grouping.
First one is to use $(LD) instead of $(CXX) when linking.
Second one is to make all link commands Make recursive by prepending them with a +.
Third one is to make use of -flto=jobserver on Vita builds instead of hardcoding a 20 cores value which can have negative impacts on some servers.