linking small programs with AC_LINK_IFELSE

[Bob Rossi]

Hi,

I'm wondering. I'm trying to use AC_LINK_IFELSE to link a small program
against libexpat. I set the flags 
  LIBS="$LIBS $EXPAT_LDADD"
  CPPFLAGS="$CPPFLAGS $EXPAT_INCLUDES"
  LDFLAGS="$LDFLAGS $EXPAT_LDFLAGS"
appropriatly. 

The problem is, I use the program to determine if libexpat has been
compiled already. If that doesn't work, I go ahead and ./configure &&
make the libexpat that i've packed in my distro. Now, if libexpat is
already installed on the system, this test always passes, because gcc
finds it in the standard location. Is there anything I can do to force
gcc and autoconf to link that program and only use the libraries and
headers that I give it?

Thanks,
Bob Rossi