bug#34527: 27.0.50; Cygwin now has timer_getoverrun

[Ken Brown <kbrown@cornell.edu>]

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The latest release of Cygwin supports the timer_getoverrun function, so
there's no longer a need for the workaround in profiler.c that defines
timer_getoverrun as a macro.  The attached patch causes the function to
be used rather than the macro when it exists.

OK for master?

Ken

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From 162aa52538d38a0ca7f7969f79b1e1cd7f708e3c Mon Sep 17 00:00:00 2001
From: Ken Brown <kbrown@cornell.edu>
Date: Sun, 17 Feb 2019 12:10:26 -0500
Subject: [PATCH] Use 'timer_getoverrun' on Cygwin when possible

* configure.ac: Add a check for the 'timer_getoverrun' function.

* src/profiler.c [CYGWIN] : Define 'timer_getoverrun' as a
macro only on versions of Cygwin where it is not already
defined as a function.
---
 configure.ac   | 2 +-
 src/profiler.c | 7 ++++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/configure.ac b/configure.ac
index 58579008f3..c26eb6d1e8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4126,7 +4126,7 @@ AC_DEFUN
 lrand48 random rint trunc \
 select getpagesize setlocale newlocale \
 getrlimit setrlimit shutdown \
-pthread_sigmask strsignal setitimer \
+pthread_sigmask strsignal setitimer timer_getoverrun \
 sendto recvfrom getsockname getifaddrs freeifaddrs \
 gai_strerror sync \
 getpwent endpwent getgrent endgrent \
diff --git a/src/profiler.c b/src/profiler.c
index 15a0eef0d3..293e52633a 100644
--- a/src/profiler.c
+++ b/src/profiler.c
@@ -232,9 +232,10 @@ static EMACS_INT current_sampling_interval;
 
 /* Signal handler for sampling profiler.  */
 
-/* timer_getoverrun is not implemented on Cygwin, but the following
-   seems to be good enough for profiling. */
-#ifdef CYGWIN
+/* timer_getoverrun is not implemented on Cygwin prior to
+   cygwin-3.0.0, but the following seems to be good enough for
+   profiling. */
+#if defined CYGWIN && !defined HAVE_TIMER_GETOVERRUN
 #define timer_getoverrun(x) 0
 #endif
 
-- 
2.17.0