fix building under Linux

postfix/postfix.spec

@@ -131,6 +131,9 @@ Provides:     MTA
     %{l_rpmtool} subst \
         's;config_directory/postfix-script;command_directory/postfix-script;' \
         -- conf/postfix-script*
+    %{l_rpmtool} subst \
+        's;/usr/include;%{l_prefix}/include;g' \
+        -- makedefs
 
 %build