Cygwin: let feraiseexcept actually raise an exception

The exception handling inside of Cygwin functions marked as SIGFE
covers exceptions and lets the library code handle them gracefully.
If these functions want to raise an exception, they have to send a
signal explicitely via raise(3).

That's not what we want in feraiseexcept(). It triggers a floating
point exception explicitely by calling the i387 op "fwait".  Being
marked as SIGFE, this exception will be suppressed and the normal
exception handling won't kick in.

Fix this by moving feraiseexcept into the NOSIGFE realm.

Fixes: 0f81b5d4bcaa ("* Makefile.in (DLL_OFILES): Add new fenv.o module.")
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/cygwin.din

@@ -534,7 +534,7 @@ fegetround NOSIGFE
 feholdexcept SIGFE
 feof SIGFE
 feof_unlocked SIGFE
-feraiseexcept SIGFE
+feraiseexcept NOSIGFE
 ferror SIGFE
 ferror_unlocked SIGFE
 fesetenv SIGFE

winsup/cygwin/release/3.4.10

@@ -6,3 +6,6 @@ Bug Fixes
 
 - Fix hang in process initialization if cwd is unreadable.
   Addresses: https://cygwin.com/pipermail/cygwin/2023-October/254604.html
+
+- Let feraiseexcept actually raise an exception.
+  Addresses: https://cygwin.com/pipermail/cygwin/2023-October/254667.html