[newlib-cygwin] Cygwin: fix CPU_SET macro visibility

[Ken Brown]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=a083a4f2661dd465b30e508fca343f678421762f

commit a083a4f2661dd465b30e508fca343f678421762f
Author: Mark Geisert <mark@maxrnd.com>
Date:   Fri Sep 13 21:58:02 2019 -0700

    Cygwin: fix CPU_SET macro visibility
    
    The CPU_SET macros defined in Cygwin's include/sys/cpuset.h must not
    be visible in an application's namespace unless _GNU_SOURCE has been
    #defined.  Internally this means wrapping them in #if __GNU_VISIBLE.

Diff:
---
 winsup/cygwin/include/sys/cpuset.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/winsup/cygwin/include/sys/cpuset.h b/winsup/cygwin/include/sys/cpuset.h
index 2056f6a..1adf48d 100644
--- a/winsup/cygwin/include/sys/cpuset.h
+++ b/winsup/cygwin/include/sys/cpuset.h
@@ -26,6 +26,7 @@ typedef struct
   __cpu_mask __bits[__CPU_GROUPMAX];
 } cpu_set_t;
 
+#if __GNU_VISIBLE
 int __sched_getaffinity_sys (pid_t, size_t, cpu_set_t *);
 
 /* These macros alloc or free dynamically-sized cpu sets of size 'num' cpus.
@@ -88,6 +89,8 @@ int __sched_getaffinity_sys (pid_t, size_t, cpu_set_t *);
 #define CPU_XOR(dst, src1, src2)  CPU_XOR_S(sizeof (cpu_set_t), dst, src1, src2)
 #define CPU_EQUAL(src1, src2)     CPU_EQUAL_S(sizeof (cpu_set_t), src1, src2)
 
+#endif /* __GNU_VISIBLE */
+
 #ifdef __cplusplus
 }
 #endif