Revisit default link flags
Submitted by Xavier Claessens
In bug #788771 it has been proposed to add -Wlz,relro and -Wlz,now but it has performance concerns. We should discuss here if we should/shoudn't add those flags. Ideally with performance measurements.
Also we could consider removing --disable-bsymbolic, it is currently used by refdbg and Debian has a package that builds glib with it, but it's probably a thing of the past.