[newlib-cygwin] Cygwin: make pthread_yield available for internal usage

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=5999c433bbc16c00385a2157dab9c416f8000f6b

commit 5999c433bbc16c00385a2157dab9c416f8000f6b
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Sat Aug 29 21:21:21 2020 +0200

    Cygwin: make pthread_yield available for internal usage
    
    In preparation of importing FreeBSDs stdthreads functions,
    change the way pthread_yield is exported, so that the symbol
    can be used internally as well.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/common.din | 2 +-
 winsup/cygwin/sched.cc   | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/winsup/cygwin/common.din b/winsup/cygwin/common.din
index a7b4aa2b0..d781922a3 100644
--- a/winsup/cygwin/common.din
+++ b/winsup/cygwin/common.din
@@ -1159,7 +1159,7 @@ pthread_suspend SIGFE
 pthread_testcancel SIGFE
 pthread_timedjoin_np SIGFE
 pthread_tryjoin_np SIGFE
-pthread_yield = sched_yield SIGFE
+pthread_yield SIGFE
 ptsname SIGFE
 ptsname_r SIGFE
 putc SIGFE
diff --git a/winsup/cygwin/sched.cc b/winsup/cygwin/sched.cc
index fdb8ba738..84df7b9e6 100644
--- a/winsup/cygwin/sched.cc
+++ b/winsup/cygwin/sched.cc
@@ -411,6 +411,7 @@ sched_yield ()
   SwitchToThread ();
   return 0;
 }
+EXPORT_ALIAS (sched_yield, pthread_yield)
 
 int
 sched_getcpu ()