How do we detect release mode in autoconf or in configure script?

Hi,

As I wrote in another thread, Subversion's configure script in release
mode still has an issue that it detects SWIG executable which is never
used in release mode.

To resolve this issue, it is need to detect release mode in autoconf
macro or in generated configure script. However I can't find the ways
already used in autoconf input files.

What is the recommended way to do it?

Or if there is no recommended way, may I add a code fragment like
the following to configure.ac?

[[[
# detect release mode
if $GREP -q '^RELEASE_MODE[[:blank:]]*=[[:blank:]]*1' $abs_src_dir/build-outputs.mk; then
  release_mode = yes
else
  release_mode = no
fi
]]]

Thanks,

-- 
Yasuhito FUTATSUKI <futatuki_at_yf.bsclub.org>