bash-completion: Fix/improve generator names extraction

Docs/bash-completion/cmake

@@ -100,11 +100,13 @@ _cmake()
             return
             ;;
         -G)
-            # FIXME: doesn't work properly
             local IFS=$'\n'
+            local quoted
+            printf -v quoted %q "$cur"
             COMPREPLY=( $( compgen -W '$( cmake --help 2>/dev/null | sed -n \
-                "/^.*[^ ].*= Generates/{s|^ *\(.*[^ ]\) *= Generates.*$|\1|;s| |\\\\ |g;p}" \
-                2>/dev/null )' -- "$cur" ) )
+                -e "1,/^Generators/d" \
+                -e "/^  *[^ =]/{s|^ *\([^=]*[^ =]\).*$|\1|;s| |\\\\ |g;p}" \
+                2>/dev/null )' -- "$quoted" ) )
             return
             ;;
         --help-command)

Docs/bash-completion/cpack

@@ -8,8 +8,8 @@ _cpack()
     case "$prev" in
         -G)
             COMPREPLY=( $( compgen -W '$( cpack --help 2>/dev/null |
-                grep "^  .*= .*" 2> /dev/null | grep -v "^  -" 2>/dev/null |
-                cut -d" " -f 3 )' -- "$cur" ) )
+                sed -e "1,/^Generators/d" -e "s|^ *\([^ ]*\) .*$|\1|" \
+                2>/dev/null )' -- "$cur" ) )
             return
             ;;
         -C)