fix build on SLE_11_SP1/2

OBS-URL: https://build.opensuse.org/package/show/network:utilities/netsniff-ng?expand=0&rev=12

netsniff-ng.spec

@@ -12,6 +12,8 @@
 
 # Please submit bugfixes or comments via http://bugs.opensuse.org/
 
+%define bison_version %(rpm -q --qf='%{VERSION}' bison | %__perl -n -e 'print $1 * 100 + $2 if /^(\d+)\.(\d+)/')
+
 Name:           netsniff-ng
 Version:        0.5.6
 Release:        0
@@ -32,8 +34,15 @@ BuildRequires:  liburcu-devel
 %else
 %define with_nf 0
 %endif
-BuildRequires:  flex
+BuildRequires:  bison
+%if 0%{?bison_version} >= 250
 BuildRequires:  bison >= 2.5
+BuildRequires:  flex
+%define with_bison 1
+%else
+BuildConflicts: flex
+%define with_bison 0
+%endif
 BuildRequires:  cmake >= 2.8
 BuildRequires:  gcc make glibc-devel
 BuildRequires:  autoconf automake libtool
@@ -79,15 +88,17 @@ popd
 %doc THANKS Documentation
 %config %{_sysconfdir}/netsniff-ng
 %{_sbindir}/ashunt
-%{_sbindir}/bpfc
 %{_sbindir}/ifpps
 %{_sbindir}/netsniff-ng
 %{_sbindir}/trafgen
 %doc %{_mandir}/man8/ashunt.8*
-%doc %{_mandir}/man8/bpfc.8*
 %doc %{_mandir}/man8/ifpps.8*
 %doc %{_mandir}/man8/netsniff-ng.8*
 %doc %{_mandir}/man8/trafgen.8*
+%if %with_bison
+%{_sbindir}/bpfc
+%doc %{_mandir}/man8/bpfc.8*
+%endif
 %if %with_nf
 %{_sbindir}/flowtop
 %doc %{_mandir}/man8/flowtop.8*