[newlib-cygwin] cygwin: document XSI sigpause

[Yaakov Selkowitz]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=a5cc86ba1306f986b888edf583a3a3ca6c1d98a8

commit a5cc86ba1306f986b888edf583a3a3ca6c1d98a8
Author: Yaakov Selkowitz <yselkowi@redhat.com>
Date:   Wed Jun 14 14:30:44 2017 -0500

    cygwin: document XSI sigpause
    
    Signed-off-by: Yaakov Selkowitz <yselkowi@redhat.com>

Diff:
---
 winsup/cygwin/release/2.8.1 | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/winsup/cygwin/release/2.8.1 b/winsup/cygwin/release/2.8.1
index 90b5a66..1ebe7d8 100644
--- a/winsup/cygwin/release/2.8.1
+++ b/winsup/cygwin/release/2.8.1
@@ -9,6 +9,9 @@ What's new:
 What changed:
 -------------
 
+- The XSI form of sigpause, which removes the given signal from the process's
+  signal mask, is made available when compiling with _XOPEN_SOURCE or
+  _GNU_SOURCE.
 
 Bug Fixes
 ---------