i3bar: Do not kill watcher on EOF
i3bar: Do not kill watcher on EOF

Wait for the child process to exit on its own before freeing
watcher-related resources.

i3bar shows the last received status line until the process exits.

Fixes a race condition where the termination signal was sometimes not
received to display a meaningful error message.

shdown/i3,tcreech/i3,saksham0808/i3,pronobis/i3,FauxFaux/i3,ccryx/i3,cornerman/i3,gnomus/i3-wm-gap,pronobis/i3,yin/i3,cornerman/i3,simonnagl/i3,jubalh/i3,Kaligule/i3,EvilPudding/i3,FauxFaux/i3,mariusmuja/i3wm,saksham0808/i3,tcreech/i3,renlinx007/i3wm,Airblader/i3-original,simonnagl/i3,gnomus/i3-wm-gap,saksham0808/i3,Airblader/i3,drbig/i3,Airblader/i3,simonnagl/i3,yin/i3,Matmusia/i3,Zopieux/i3,cornerman/i3,netzverweigerer/i3,renlinx007/i3wm,avrelaun/i3,mariusmuja/i3wm,stapelberg/i3,sideffect0/i3wm,mariusmuja/i3wm,renlinx007/i3wm,dg-ratiodata/i3,renlinx007/i3wm,Kaligule/i3,ccryx/i3,Matmusia/i3,netzverweigerer/i3,tcreech/i3,acrisci/i3,acrisci/i3,EvilPudding/i3,Azkae/i3,acrisci/i3,EvilPudding/i3,Airblader/i3-original,sideffect0/i3wm,stapelberg/i3,Airblader/i3-original,dg-ratiodata/i3,MForster/i3,Zopieux/i3,yin/i3,stapelberg/i3,Airblader/i3,Chr1stoph/i3,shdown/i3,gnomus/i3-wm-gap,cornerman/i3,dg-ratiodata/i3,isharp/i3,Zopieux/i3,acrisci/i3,sideffect0/i3wm,strake/i3,gnomus/i3-wm-gap,Zopieux/i3,shdown/i3,isharp/i3,pronobis/i3,Azkae/i3,jubalh/i3,Matmusia/i3,mariusmuja/i3wm,jubalh/i3,smrt28/i3,shdown/i3,dg-ratiodata/i3,MForster/i3,Azkae/i3,MForster/i3,Chr1stoph/i3,i3/i3,mh21/i3,tcreech/i3,Kaligule/i3,strake/i3,sideffect0/i3wm,i3/i3,MForster/i3,simonnagl/i3,Matmusia/i3,smrt28/i3,strake/i3,acrisci/i3,ccryx/i3,Chr1stoph/i3,saksham0808/i3,Airblader/i3-original,strake/i3,drbig/i3,i3/i3,mh21/i3,Airblader/i3,drbig/i3,isharp/i3,Chr1stoph/i3,i3/i3,smrt28/i3,pronobis/i3,isharp/i3,Airblader/i3-original,ccryx/i3,stapelberg/i3,avrelaun/i3,avrelaun/i3,drbig/i3,avrelaun/i3,Azkae/i3,jubalh/i3,EvilPudding/i3,FauxFaux/i3,smrt28/i3,FauxFaux/i3,strake/i3,yin/i3,mh21/i3,netzverweigerer/i3,netzverweigerer/i3,Kaligule/i3,mh21/i3