Warn if -o is used in combination with -C
Warn if -o is used in combination with -C

GNOME/vala,flobrosch/vala-fixes,frida/vala,frida/vala,flobrosch/vala-fixes,GNOME/vala,GNOME/vala,spidermonkdust/vala,rvu95/vala,rvu95/vala,rvu95/vala,frida/vala,spidermonkdust/vala,frida/vala,spidermonkdust/vala,GNOME/vala,flobrosch/vala-fixes,frida/vala