patch 8.1.0124: has('vcon') returns true even for non-win32 terminal

Problem:    has('vcon') returns true even for non-win32 terminal.
Solution:   Check the terminal type. (Nobuhiro Takasaki, closes #3106)

src/evalfunc.c

@@ -6609,7 +6609,7 @@ f_has(typval_T *argvars, typval_T *rettv)
 #endif
 #ifdef FEAT_VTP
 	else if (STRICMP(name, "vcon") == 0)
-	    n = has_vtp_working();
+	    n = is_term_win32() && has_vtp_working();
 #endif
 #ifdef FEAT_NETBEANS_INTG
 	else if (STRICMP(name, "netbeans_enabled") == 0)

src/version.c

@@ -789,6 +789,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    124,
 /**/
     123,
 /**/