Fix C compatibility issue in the configure script

Related to:

  <https://fedoraproject.org/wiki/Changes/PortingToModernC>
  <https://fedoraproject.org/wiki/Toolchain/PortingToModernC>

libxcrypt-configure-c99.patch

@@ -0,0 +1,35 @@
+Author: Florian Weimer <fweimer@redhat.com>
+Date:   Tue Dec 19 11:00:11 2023 +0100
+
+    configure: Only text the makecontext signature we need
+    
+    The test/explicit-bzero.c test uses a start routine without any
+    arguments.  There is no need for the multi-argument version.
+    
+    This avoids a build failure with glibc and future compilers.
+    The GNU C library declares the makecontext callback of
+    type void (*) (void), so no cast is needed.  On other systems,
+    the type may be the (currently distinct) type void (*) (),
+    but given that this only affects the ability to execute a test,
+    no further machinery is added here to detect that different type.
+
+Submitted upstream: <https://github.com/besser82/libxcrypt/pull/178>
+
+diff --git a/configure.ac b/configure.ac
+index 35965b3b20466f71..ecc71b02b8c9752f 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -303,13 +303,11 @@ AS_IF([test $ac_cv_header_ucontext_h = yes],
+ #include <ucontext.h>
+ static int x;
+ static void fn1(void) {}
+-static void fn2(int a, int b) { x = a - b; }
+ ]], [[
+   ucontext_t uc1, uc2;
+   if (getcontext(&uc1)) return 1;
+   if (setcontext(&uc1)) return 1;
+   makecontext(&uc1, fn1, 0);
+-  makecontext(&uc2, fn2, 2, 1, 1);
+   if (swapcontext(&uc1, &uc2)) return 1;
+   return x;
+ ]])],

libxcrypt.spec

@@ -168,7 +168,7 @@ fi                                          \
 
 Name:           libxcrypt
 Version:        4.4.36
-Release:        2%{?dist}
+Release:        3%{?dist}
 Summary:        Extended crypt library for descrypt, md5crypt, bcrypt, and others
 
 # For explicit license breakdown, see the
@@ -179,6 +179,7 @@ Source0:        %{url}/releases/download/v%{version}/%{name}-%{version}.tar.xz
 Source1:        %{url}/releases/download/v%{version}/%{name}-%{version}.tar.xz.asc
 Source2:        %{url}/releases/download/v%{version}/%{name}-gpgkey.gpg
 Source3:        %{url}/releases/download/v%{version}/%{name}-%{version}.tar.xz.sha256sum
+Patch0: libxcrypt-configure-c99.patch
 
 # Patch 0000 - 2999: Backported patches from upstream.
 
@@ -584,6 +585,9 @@ done
 
 
 %changelog
+* Tue Dec 19 2023 Florian Weimer <fweimer@redhat.com> - 4.4.36-3
+- Fix C compatibility issue in the configure script
+
 * Thu Jul 20 2023 Fedora Release Engineering <releng@fedoraproject.org> - 4.4.36-2
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild