Add BR:gcc and spec file modernization

diffstat.spec

@@ -8,6 +8,8 @@ URL: http://invisible-island.net/diffstat
 Source0: ftp://ftp.invisible-island.net/pub/diffstat/%{name}-%{version}.tgz
 # Taken from diffstat.c.
 Source1: COPYING
+
+BuildRequires: gcc
 BuildRequires: xz
 
 %description
@@ -24,22 +26,25 @@ diff command's output.
 
 %build
 %configure
-make %{?_smp_mflags}
+%make_build
 
 %install
-rm -rf $RPM_BUILD_ROOT
-make DESTDIR=$RPM_BUILD_ROOT install
+%make_install
 cp %{SOURCE1} .
 
 %check
 make check
 
 %files
-%doc COPYING CHANGES README
+%license COPYING
+%doc CHANGES README
 %{_bindir}/diffstat
 %{_mandir}/*/*
 
 %changelog
+* Thu Jul 19 2018 Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> - 1.61-8
+- Add BR:gcc and spec file modernization
+
 * Thu Jul 12 2018 Fedora Release Engineering <releng@fedoraproject.org> - 1.61-8
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_29_Mass_Rebuild