GC-LINE-STYLE is :DASH, not :ON-OFF-DASH

Commit from #209 introduced a change that was not backward compatible breaking
preexisting software. I've updated tests too.

gcontext.lisp

@@ -226,7 +226,7 @@
 (def-gc-accessor foreground card32)
 (def-gc-accessor background card32)
 (def-gc-accessor line-width card16)
-(def-gc-accessor line-style (member :solid :on-off-dash :double-dash))
+(def-gc-accessor line-style (member :solid :dash :double-dash))
 (def-gc-accessor cap-style (member :not-last :butt :round :projecting))
 (def-gc-accessor join-style (member :miter :round :bevel))
 (def-gc-accessor fill-style (member :solid :tiled :stippled :opaque-stippled))

manual/clx.texinfo

@@ -5796,15 +5796,15 @@ than the odd dashes. The @var{:butt} style is used where even and odd
 dashes meet (see paragraph 5.4.7, Fill-Rule and
 Fill-Style).
 
-@item :on-off-dash
+@item :dash
 Only the even dashes are drawn, with cap-style applied to all internal
 ends of the individual dashes, except @var{:not-last} is treated as
 @var{:butt}.
 @end table
 
 @table @var
 @item line-style
-One of @var{:on-off-dash}, @var{:double-dash}, or @var{:solid}.
+One of @var{:dash}, @var{:double-dash}, or @var{:solid}.
 @end table
 
 @end defun

tests/core-protocol.lisp

@@ -426,11 +426,11 @@
       (is (equalp (xlib:gcontext-join-style gc) :round))
       (is (member (xlib:gcontext-line-style gc) '(:solid
                                                   :double-dash
-                                                  :on-off-dash)))
+                                                  :dash)))
       (finishes (setf (xlib:gcontext-line-style gc) :double-dash))
       (is (equalp (xlib:gcontext-line-style gc) :double-dash))
-      (finishes (setf (xlib:gcontext-line-style gc) :on-off-dash))
-      (is (equalp (xlib:gcontext-line-style gc) :on-off-dash))
+      (finishes (setf (xlib:gcontext-line-style gc) :dash))
+      (is (equalp (xlib:gcontext-line-style gc) :dash))
       (is (typep (xlib:gcontext-line-width gc) 'xlib:card16))
       (is (xlib:gcontext-p gc))
       (is (not (xlib:gcontext-p root-window)))