mingw: Bump minimum supported Fedora version to 28

Should have been part of 2569ba13, but clearly wasn't.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

mingw-libvirt.spec.in

@@ -3,7 +3,7 @@
 # This spec file assumes you are building on a Fedora version
 # that's still supported by the vendor. It may work on other distros
 # or versions, but no effort will be made to ensure that going forward.
-%define min_fedora 26
+%define min_fedora 28
 
 %if 0%{?fedora} && 0%{?fedora} >= %{min_fedora}
     %define supported_platform 1
@@ -72,11 +72,7 @@ BuildRequires:  pkgconfig
 BuildRequires:  gettext
 BuildRequires:  libxslt
 BuildRequires:  python3
-%if 0%{?fedora} >= 27
 BuildRequires:  perl-interpreter
-%else
-BuildRequires:  perl
-%endif
 BuildRequires:  perl(Getopt::Long)
 %if 0%{?enable_autotools}
 BuildRequires: autoconf