Recreate configure unconditionally

Previous fix did not work, because new configure was not regenerated
after changing configure.ac. Make new configure on every build.

Resolves: RHEL-147790

unbound.spec

@@ -106,9 +106,11 @@ BuildRequires: systemd-rpm-macros
 %else
 BuildRequires: systemd
 %endif
-# Required for SVN versions
-# BuildRequires: bison
-# BuildRequires: automake autoconf libtool
+# Required for snapshot versions or modified configure.ac
+BuildRequires: bison
+BuildRequires: automake
+BuildRequires: autoconf
+BuildRequires: libtool
 
 # Needed because /usr/sbin/unbound links unbound libs staticly
 Requires: %{name}-libs%{?_isa} = %{version}-%{release}
@@ -231,7 +233,7 @@ pushd %{pkgname}
 %autopatch -p2
 
 # only for snapshots
-# autoreconf -iv
+autoreconf -fiv
 
 # copy common doc files - after here, since it may be patched
 cp -pr doc pythonmod libunbound ../
@@ -252,9 +254,6 @@ cp -a %{dir_primary} %{dir_secondary}
 %endif
 
 %build
-# This is needed to rebuild the configure script to support Python 3.x
-# autoreconf -iv
-
 # ./configure script common arguments
 %global configure_args --with-libevent --with-pthreads --with-ssl \\\
             --disable-rpath --disable-static \\\