wrlib: mark the script 'get-wraster-flags' as deprecated

This script should have been removed a long time ago, in favour of
pkg-config which has to be present anyway to compile Window Maker.

This patch makes the script print a warning about it, and now calls itself
pkg-config, instead of being generated; the man page was also updated
accordingly (and spell-checked).

Signed-off-by: Christophe CURIS <christophe.curis@free.fr>

.gitignore

@@ -61,7 +61,6 @@ util/wmsetup
 util/wxcopy
 util/wxpaste
 
-wrlib/get-wraster-flags
 wrlib/tests/testdraw
 wrlib/tests/testgrad
 wrlib/tests/testrot