Don't use -w (treat warnings as errors) in default _d_optflags

Instead, use -wi (treat warnings as informational) for distro builds so
that new warnings don't break package builds.

While at this, also sync _d_optflags with Debian's DFLAGS and drop
unused _d_libdir definition.

ldc.spec

@@ -212,6 +212,7 @@ install -m0644 phobos.d.tags %{buildroot}/%{_datadir}/geany/tags/
 * Mon Aug 16 2021 Kalev Lember <klember@redhat.com> - 1:1.27.1-1
 - Update to 1.27.1
 - Build with llvm 12
+- Don't use -w (treat warnings as errors) in default _d_optflags
 
 * Thu Jul 22 2021 Fedora Release Engineering <releng@fedoraproject.org> - 1:1.25.1-2
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_35_Mass_Rebuild

macros.ldc

@@ -3,7 +3,5 @@
 #
 # Include directory where all .di or .d file are installed.
 %_d_includedir %{_includedir}/d
-# Compile options for ldc and make file
-%_d_optflags -release -w -g -O1
-# Lib directory path
-%_d_libdir %{_libdir}/d/
+# Default D optimization flags for LDC
+%_d_optflags -O -g -release -wi