devel/sis: Fix building the SIS on FreeBSD

- Update to SIS 2.17 which has internal readline support for
  the hosts which do not have readline.

Closes #3763

source-builder/config/sis-2-1.cfg

@@ -31,26 +31,19 @@ Release:   %{release}
 
   cd sis-%{sis_version}
 
-  ac_prefix=%{_prefix}
-
-  if test "%{_build}" != "%{_host}" ; then
-    CFLAGS_FOR_BUILD="-g -O2 -Wall"
-  fi
-  export CFLAGS CFLAGS_FOR_BUILD CC
-
   if test "%{_target}" != "" ; then
     SIS_PREFIX="%{_target}-"
   fi
-  CFLAGS="$SB_CFLAGS" \
+
+  %{host_build_flags}
+
   ./configure \
-    --build=%{_build} --host=%{_host} \
+    --build=%{_build} --host=%{_host} --target=%{_target} \
     --program-prefix="$SIS_PREFIX" \
-    --prefix=${ac_prefix}
+    --prefix=${_prefix}
 
   %{__make} %{?_smp_mflags} all
 
-  unset CFLAGS_FOR_BUILD
-
   cd ${build_top}
 
 %install