Fixed typo in a comment.

Deleted bogus comment.
Added debugging support.

hw/xfree86/os-support/shared/sigio.c

@@ -259,17 +259,25 @@ int
 xf86BlockSIGIO (void)
 {
     sigset_t	set, old;
-
+    int		ret;
+    
     sigemptyset (&set);
     sigaddset (&set, SIGIO);
     sigprocmask (SIG_BLOCK, &set, &old);
-    return sigismember (&old, SIGIO);
+    ret = sigismember (&old, SIGIO);
+#ifdef DEBUG
+    ErrorF("%i = xf86BlockSIGIO()\n",ret);
+#endif
+    return ret; 
 }
 
 void
 xf86UnblockSIGIO (int wasset)
 {
     sigset_t	set;
+#ifdef DEBUG
+    ErrorF("xf86UnblockSIGIO(%i)\n",wasset);
+#endif
 
     if (!wasset)
     {