Add C++ support to compiler script. (#828)

.local/bin/compiler

@@ -30,6 +30,7 @@ case "$ext" in
 	[0-9]) preconv "$file" | refer -PS -e | groff -mandoc -T pdf > "$base".pdf ;;
 	c) cc "$file" -o "$base" && "$base" ;;
 	go) go run "$file" ;;
+	cpp) g++ "$file" -o "$base" && "$base" ;;
 	h) sudo make install ;;
 	m) octave "$file" ;;
 	md)	if  [ -x "$(command -v lowdown)" ]; then