Cygwin: add latest signal handling fixes to release notes

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/release/3.0.6

@@ -9,6 +9,11 @@ What changed:
 Bug Fixes
 ---------
 
-- Fix the problem that `ps' or `pstree' may show up in their own
+- Fix the problem that `ps' or `pstree' may show up in their own output twice.
-  output twice.
   Addresses: Report on IRC
+
+- Honor setting uc_sigmask in a sigaction signal handler.
+  Addresses: https://cygwin.com/ml/cygwin/2019-04/msg00016.html
+
+- Fix signal handling if setcontext is called from a signal handler.
+  Addresses: Self-tested.

winsup/cygwin/release/3.1.0

@@ -13,6 +13,9 @@ What changed:
   Addresses: https://cygwin.com/ml/cygwin/2015-03/msg00047.html
              https://cygwin.com/ml/cygwin/2015-12/msg00311.html
 
+- If a SA_SIGINFO signal handler changes the ucontext_t pointed to by
+  the third parameter, follow it after returning from the handler.
+
 
 Bug Fixes
 ---------

winsup/doc/new-features.xml

@@ -18,6 +18,11 @@ Add 24 bit color support using xterm compatibility mode in Windows 10
 uses the nearest color from 16 system colors.
 </para></listitem>
 
+<listitem><para>
+If a SA_SIGINFO signal handler changes the ucontext_t pointed to by the
+third parameter, follow it after returning from the handler.
+</para></listitem>
+
 </itemizedlist>
 
 </sect2>