patch 8.0.0585: test_options fails when run in the GUI

Problem:    Test_options fails when run in the GUI.
Solution:   Also check the 'imactivatekey' value when the GUI is not running.
            Specify test values that work and that fail.

src/option.c

@@ -6403,7 +6403,7 @@ did_set_string_option(
 #if defined(FEAT_XIM) && defined(FEAT_GUI_GTK)
     else if (varp == &p_imak)
     {
-	if (gui.in_use && !im_xim_isvalid_imactivate())
+	if (!im_xim_isvalid_imactivate())
 	    errmsg = e_invarg;
     }
 #endif

src/testdir/gen_opt_test.vim

@@ -96,6 +96,7 @@ let test_values = {
       \ 'guifontwide': [['', 'fixedsys'], []],
       \ 'helplang': [['', 'de', 'de,it'], ['xxx']],
       \ 'highlight': [['', 'e:Error'], ['xxx']],
+      \ 'imactivatekey': [['', 'S-space'], ['xxx']],
       \ 'isfname': [['', '@', '@,48-52'], ['xxx', '@48']],
       \ 'isident': [['', '@', '@,48-52'], ['xxx', '@48']],
       \ 'iskeyword': [['', '@', '@,48-52'], ['xxx', '@48']],

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    585,
 /**/
     584,
 /**/