caching variables

[dave]

Hello;

I am using bash and Fedora.

I have had this problem for a while, but haven't figured it out yet.
When I change environment variables sometimes in a nested autoconf /
configure software structure, I cannot get the old value to stop
appearing in the configuration:

Here is what I mean

Inside the old source-nav tree it calls for the obsolete 

-fwritable-strings  CFLAGS option 

Inside source/itcl/itcl/unix configure.in is 

if test "$itcl_cv_prog_gcc" = "yes" ; then
    CFLAGS="$CFLAGS -fwritable-strings -Wshadow -Wtraditional -Wall"
fi

Now when I take out -fwritable-strings and autoreconf, it still includes
that in the configure  here is the line in config.log:

configure:3516: result: yes
configure:3532: checking default compiler flags
configure:3541: result: -fwritable-strings -Wshadow -Wtraditional -Wall

checking default compiler flags... -fwritable-strings -Wshadow
-Wtraditional -Wall


How do I clear out old cache variables or make sure it doesn't take the
old values?

Thank you,

Dave