Fix build with package notes

The issue that in %prep the flags are sligtly different than in %build
or %install (%buildsubdir is not set), and we end up with the wrong
path in the Makefile, see rhbz#2055863.

This moves the sed into %build, which is somewhat ugly, but solves the
issue. The sequence of commands that is executed is the same, except
that the sed is invoked as first thing in %build, not as the last in
%prep. I think that for such a simple package this is acceptable, and
it's not worth waiting for a "proper" solution (which will likely
require some new funtionality in rpm).

argon2.spec

@@ -18,7 +18,7 @@
 
 Name:    argon2
 Version: %{upstream_version}%{?upstream_prever:~%{upstream_prever}}
-Release: 8%{?dist}
+Release: 9%{?dist}
 Summary: The password-hashing tools
 
 License: Public Domain or ASL 2.0
@@ -88,6 +88,7 @@ fi
 # Fix pkgconfig file
 sed -e 's:lib/@HOST_MULTIARCH@:%{_lib}:;s/@UPSTREAM_VER@/%{version}/' -i %{libname}.pc
 
+%build
 # Honours default RPM build options and library path, do not use -march=native
 sed -e '/^CFLAGS/s:^CFLAGS:LDFLAGS=%{build_ldflags}\nCFLAGS:' \
     -e 's:-O3 -Wall:%{optflags}:' \
@@ -96,7 +97,6 @@ sed -e '/^CFLAGS/s:^CFLAGS:LDFLAGS=%{build_ldflags}\nCFLAGS:' \
     -e 's:CFLAGS += -march=\$(OPTTARGET)::' \
     -i Makefile
 
-%build
 # parallel build is not supported
 make -j1
 
@@ -135,6 +135,9 @@ make test
 
 
 %changelog
+* Mon Mar 28 2022 Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> - 20171227-9
+- Fix build with package notes (rhbz#2066558)
+
 * Wed Jan 19 2022 Fedora Release Engineering <releng@fedoraproject.org> - 20171227-8
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_36_Mass_Rebuild