Backport r60537: have order of CPPFLAGS and LDFLAGS be honored.
diff --git a/setup.py b/setup.py
index 99ad7e3..22fc2b1 100644
--- a/setup.py
+++ b/setup.py
@@ -277,7 +277,7 @@
                 parser.add_option(arg_name, dest="dirs", action="append")
                 options = parser.parse_args(env_val.split())[0]
                 if options.dirs:
-                    for directory in options.dirs:
+                    for directory in reversed(options.dirs):
                         add_dir_to_list(dir_list, directory)
 
         if os.path.normpath(sys.prefix) != '/usr':