Remove libunwind from dependencies

In the case where a C application uses zeromq and then dlopen's a C++
module, the C++ exception handling functionality will not work because
libzmg pulls in libunwind. Then the C++ module brings in libstdc++ and
libgcc_s, the personality function which is part of the C++ exception
handling the runtime finds the version of
_Unwind_GetLanguageSpecificData which is in libunwind rather than the
one that is in libgcc_s and uses that. However, version does not have
a complete implementation and so it fails causing the application to
abort. This fixes https://bugzilla.redhat.com/show_bug.cgi?id=2175966

Signed-off-by: Ben Woodard <woodard@redhat.com>

zeromq.spec

@@ -1,8 +1,9 @@
 %bcond_without pgm
+%bcond_without unwind
 
 Name:           zeromq
 Version:        4.3.4
-Release:        5%{?dist}
+Release:        6%{?dist}
 Summary:        Software library for fast, message-based applications
 
 License:        LGPLv3+
@@ -17,7 +18,10 @@ BuildRequires:  libtool
 BuildRequires:  asciidoc
 BuildRequires:  xmlto
 BuildRequires:  libsodium-devel
+
+%if %{with unwind}
 BuildRequires:  libunwind-devel
+%endif
 
 %if %{with pgm}
 BuildRequires:  openpgm-devel
@@ -63,7 +67,9 @@ autoreconf -fi
             --with-libgssapi_krb5 \
 %endif
             --with-libsodium \
+%if %{with unwind}
             --enable-libunwind \
+%endif
             --disable-Werror \
             --disable-static
 %make_build
@@ -101,6 +107,10 @@ make check V=1 || ( cat test-suite.log && exit 1 )
 
 
 %changelog
+* Tue Mar 7 2023 Ben Woodard <woodard@redhat.com> - 4.3.4-6
+- disable building with libunwind to fix C++ exceptions when a C applicaion loads
+  a module written in C++ #2175966
+
 * Sat Jan 21 2023 Fedora Release Engineering <releng@fedoraproject.org> - 4.3.4-5
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_38_Mass_Rebuild