Do not use wattr_set() if wattr_get() is unavailable to avoid resetting attrs

Author: shugo

ext/curses/curses.c

@@ -2783,7 +2783,7 @@ window_setscrreg(VALUE obj, VALUE top, VALUE bottom)
 #endif
 }
 
-#if defined(USE_COLOR) && (defined(HAVE_WCOLOR_SET) || defined(HAVE_WATTR_SET))
+#if defined(USE_COLOR) && ((defined(HAVE_WATTR_SET) && defined(HAVE_WATTR_GET)) || defined(HAVE_WCOLOR_SET))
 /*
  * Document-method: Curses::Window.color_set
  * call-seq: color_set(col)
@@ -2810,8 +2810,6 @@ window_color_set(VALUE obj, VALUE col)
 	    return Qfalse;
 	return (wattr_set(winp->window, attrs, NUM2INT(col), NULL) == OK) ? Qtrue : Qfalse;
     }
-#elif defined(HAVE_WATTR_SET)
-    return (wattr_set(winp->window, 0, NUM2INT(col), NULL) == OK) ? Qtrue : Qfalse;
 #else
     return (wcolor_set(winp->window, NUM2INT(col), NULL) == OK) ? Qtrue : Qfalse;
 #endif