codegen: Clarify handling of self for closures
codegen: Clarify handling of self for closures

jessevdk/vala,frida/vala,GNOME/vala,spidermonkdust/vala,xdave/pvala,frida/vala,flobrosch/vala-fixes,tjol/vala-tjol,spidermonkdust/vala,kamanashisroy/aroop,rvu95/vala,severinh/vala,GNOME/vala,tjol/vala-tjol,flobrosch/vala-fixes,tjol/vala-tjol,flobrosch/vala-fixes,severinh/vala,rvu95/vala,severinh/vala,GNOME/vala,GNOME/vala,frida/vala,Distrotech/vala,playya/vala,kamanashisroy/aroop,playya/vala,Distrotech/vala,playya/vala,spidermonkdust/vala,jessevdk/vala,frida/vala,rvu95/vala,jessevdk/vala,frida/vala,kamanashisroy/aroop,Distrotech/vala