patch 8.1.1101: signals test may fail in the GUI

Problem:    Signals test may fail in the GUI.
Solution:   Skip the test for the GUI. (Yee Checng Chin, closes #4202)

src/testdir/test_signals.vim

@@ -4,6 +4,11 @@ if !has('unix')
   finish
 endif
 
+if has('gui_running')
+  " Signals only work for terminals, and won't work for GUI.
+  finish
+endif
+
 source shared.vim
 
 " Test signal WINCH (window resize signal)

src/version.c

@@ -771,6 +771,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1101,
 /**/
     1100,
 /**/