posix: Add signal functions
posix: Add signal functions

Fixes bug 584145.

phako/vala,severinh/vala,GNOME/vala,jessevdk/vala,flobrosch/vala-fixes,spidermonkdust/vala,Distrotech/vala,xdave/pvala,themiwi/vala,flobrosch/vala-fixes,kamanashisroy/aroop,frida/vala,GNOME/vala,GNOME/vala,Distrotech/vala,jessevdk/vala,playya/vala,tjol/vala-tjol,kamanashisroy/aroop,rvu95/vala,tjol/vala-tjol,frida/vala,Jc2k/vala,spidermonkdust/vala,jessevdk/vala,frida/vala,rvu95/vala,Distrotech/vala,severinh/vala,severinh/vala,spidermonkdust/vala,GNOME/vala,playya/vala,tjol/vala-tjol,themiwi/vala,flobrosch/vala-fixes,rvu95/vala,frida/vala,phako/vala,Jc2k/vala,themiwi/vala,frida/vala,lovebug356/vala,playya/vala,lovebug356/vala,kamanashisroy/aroop