make post-adjustments more deterministically by first moving then removing. This way the order of the partly nested directories do not matter any more.

gcc40/gcc40.spec

@@ -242,11 +242,15 @@ Provides:     gcc = %{version}-%{release}
     #   cleanup installation tree
     mv $RPM_BUILD_ROOT%{l_prefix}/lib/lib*.a \
        $RPM_BUILD_ROOT%{l_prefix}/lib/gcc%{V_comp}/${triple}/[0-9]*/
+    dirs=""
     for multilib in `$RPM_BUILD_ROOT%{l_prefix}/bin/gcc --print-multi-lib`; do
         subdir=`echo "$multilib" | sed -e 's/;.*$//'`
         [ ".$subdir" = .. ] && continue
         mv $RPM_BUILD_ROOT%{l_prefix}/lib/$subdir/lib*.a \
            $RPM_BUILD_ROOT%{l_prefix}/lib/gcc%{V_comp}/${triple}/[0-9]*/$subdir/
+        dirs="$dirs $subdir"
+    done
+    for subdir in $dirs; do
         rm -rf $RPM_BUILD_ROOT%{l_prefix}/lib/$subdir
     done
     mv $RPM_BUILD_ROOT%{l_prefix}/${triple}/include/* \