[newlib-cygwin/main] Cygwin: add dummy implementation of _fe_nomask_env

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=d0b70afbcf510627772d509299e3d401fd515af2

commit d0b70afbcf510627772d509299e3d401fd515af2
Author:     Radek Bartoň <radek.barton@microsoft.com>
AuthorDate: Thu Jul 3 12:00:52 2025 +0200
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Mon Jul 14 14:59:26 2025 +0200

    Cygwin: add dummy implementation of _fe_nomask_env
    
    _fe_nomask_env is exported by cygwin.din but not used at all for AArch64.
    
    Signed-off-by: Radek Bartoň <radek.barton@microsoft.com>

Diff:
---
 winsup/cygwin/fenv.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/winsup/cygwin/fenv.c b/winsup/cygwin/fenv.c
index 80f7cc52ce50..1558f76c27d3 100644
--- a/winsup/cygwin/fenv.c
+++ b/winsup/cygwin/fenv.c
@@ -3,3 +3,13 @@
    being called from mainCRTStartup in crt0.o. */
 void _feinitialise (void)
 {}
+
+#if defined(__aarch64__)
+
+#include <fenv.h>
+#include <stddef.h>
+
+/* _fe_nomask_env is exported by cygwin.din but not used at all for AArch64. */
+const fenv_t *_fe_nomask_env = NULL;
+
+#endif /* __aarch64__ */